It's always possible that by now you've spent hours practising the mental exercises. You've written up your journals and discussed the results. These have developed into a working set of imagery, which you can use as a firm foundation for future work.
But then again, perhaps not. Unless you were already experienced when you started reading this sequence, it's rather more likely that you've worked on the breathing and skipped to the more interesting parts.
In truth, until now, that hasn't mattered too much. It's a bit like learning a musical instrument. Every beginner knows that they should practice scales and arpeggios, getting the underlying technique right. But actually, most beginners want to be able to play tunes right away. Which is fine, really, provided that once you've got a few tunes under your belt, you go back and practice the scales. "London's Burning" is interesting the first few times you play it, and there's a great sense of achievement in getting that far, but for most people the novelty wears off after a while. So, if you want the transcendence of Handel's "Flute-Clock" sonatas, now's the time to take a step back and work on the underlying techniques.
Make some time for shared experiences other than masturbation and intercourse (although those will continue to become more effective the more often you work together). Start by preparing for the grounding at the end: it's good discipline. If you're working last thing at night, then an alcoholic night-cap or a caffeine-free cold drink might make an appropriate ending. Prepare it now, and have it to hand. Also your journals, and a light-source bright enough to allow easy writing. Go back, perhaps, to the Dion Fortune technique of holding hands. Or, some other regular mechanism which you set aside as a signal. If you're apart, perhaps use a special candle or incense, substituting for the sense of touch.
Lie comfortably, relax and synchronise your breathing. Let the thoughts come without, at first, trying to constrain them. You must eventually build a mental image which has to be comfortable for you both, so eventually you'll want to set bounds on the experience, but for the moment, just practice letting the imagery flow. You may at first sense simple thoughts, or perhaps as faint vocalisation at the edge of hearing. One point of concentrating on breathing and relaxation is to synchronise your experiences, but another is to give the mind something else to occupy it, stopping it suppressing the images. You probably have an objective in mind, perhaps the flowing well as I've described it, perhaps something else. There is virtually no chance that your first experiences will be anything close to your intention - consider yourself lucky to get any results at all to start with. The effect is hard to describe, but even harder to actually achieve: don't give up yet.
Work for as long as you can, but eventually it will become quite obvious that there's nothing more to be gained - it's "over". Don't push - this technique has to become quite natural and it won't if you force it. If your partner hasn't finished, don't interrupt. Apart from anything else, as in other circumstances, it's only polite. But when you're both finished, share the drink, write up and then chat about the results. A good way to do this (especially if the results appear silly, as they may well at first) is to discuss them whilst cuddling erotically or indeed making love. This is not just relaxing: it helps you to superimpose the images on your partner's body, which will be useful in later working.
This is a time that will require trust in each other, and of course developing that trust is another useful side-effect. One wiccan key-phrase is "perfect trust", and it can indeed require such to share some of the imagery that may surface. You will quickly find that it can be just as difficult to discuss something absolutely stupid that occurred, as it is to mention dark or apparently unacceptable imagery. Although having a regular schedule is an advantage, don't work at this too often, If everything becomes confused or threatening, leave it for a while - you can always go quite enjoyably back to working on the physical exercises and come back to working on this later.
If, however, everything is working for you, leave the imagery to move where it will for a few sessions, and you will find that the process of discussion will eventually reach a consensus from which you can build. I'll assume that you are working within the flowing well framework, but there is no right answer - a temple, a cave, a lake or even a science fiction setting if that works for you both. But, assuming that you now have the imagery, what do you do with it?
Well, you can use it as a framework for whatever you want. It's a safe place to share together, a place where you can seek advice, or simply worship if that's important to you. It will grow in detail and assume a form of its own, greater than the sum of its parts, if you work with it and allow it to. One pleasant side-effect is that you will find you can "meet" in the place when you're apart, even sharing experiences which you might find impossible in real life. That may seem frivolous. Clearly the place is sacred and certain acts would be inappropriate, but if the celebrants would share sexuality in that context, then any act of pleasure adds fuel to the magical fire you are building.
But for many people, the most important purpose is to plan to achieve certain definite objectives, using the shared imagery, sexuality and sensuality as a focus. The last in this sequence will show an example of that, but meanwhile, I'd like to re-tell one of my favourite Graal-type tales.
There was once a wise prince, beloved of his court. But one day, hunting, he took a spear-thrust to the thigh. The wound festered and took so long to heal that by the time he was well, the leg was withered and twisted. Since a strong kingdom needs a strong ruler, the prince wanted to enter a hermitage so that his strong brother could rule in his stead. But the courtiers loved the prince so much that they went to a famous local magician and healer and asked her for a potion which would make the prince's leg whole once again.
She thought for a little while, and then said "Apply a potion of equal parts of the yellow wort from the well, the green wrack from the sea at the Bay of the Ancients, the blue flowers which grow by the standing stones on the moor and the purple heather from the top of Mount Morn. But the prince must pick the plants himself if the cure is to work."
So, the whole court set off for the well, with the prince hobbling on his stout blackthorn stick. By the time he got there, he was in so much pain that he didn't want to show it to the court, so he sent most of them home, keeping only his most trusted friends with him. He picked the yellow flowers, bathed in the well many times to relieve the pain in his leg, and after a few days they set out for the bay.
By the time they arrived at the bay, they had eaten all the food they had brought with them. They collected driftwood to make a fire, and caught fish with their spears. They roasted the fish whilst the prince picked the wrack and put them in his satchel. Soon his leg was painful again, and he bathed in the sea to relieve the discomfort, and leaned on his stick. The fish tasted good after all the exercise, but once again the prince felt shamed and sent all the remaining courtiers away, save only for his page.
Alone with the page, the prince set off for the moors. They soon tired of dried fish and, since the prince was an experienced hunter, he speared rabbits and small birds for them to eat, which the page roasted. When they reached the stones, the prince set off to find the blue flowers whilst the page made camp. The flowers were hard to find, but prince limped up and down and eventually found some and put them in his satchel. That night, they ate a stew of pheasant with green herbs and roasted grain, and fell into a troubled sleep.
In the morning, the prince realised that the page was still frightened, and sent the lad home. Gritting his teeth, he set out for Mount Morn alone. The climb was hard, but part-way up he found a mountain pool in which to bathe to relieve the ache in his leg. Soon, he reached the top, and picked the blooming heather, which he put in his satchel. On the way back down, though, he slipped and dropped his stick, so that he had to complete the climb on his hands and knees.
The court was a whole day's travel, but now that he had all the ingredients for the potion, the prince wasted no time and set off. Tired and hungry, he eventually arrived and sought out the magician. She took the four ingredients and pounded them into a paste. She fed the prince a hearty bowl of stew and a draught of mead. Then she applied the paste to his leg. Sure enough, by the time he reached his hall, the leg felt better, and he was well able to partake of the feasting, and indeed many other pleasures, which awaited him.