Hmm, I would think about running about 1 plant for every 2 SQF, but that is not set in stone, but it can become a jungle before you know it. Well, you will continue tying down the branches threw the stretch during the first 2 to 3 weeks in flower and then it is really a matter of just making sure you are allowing enough light to get to the bud sights by making sure fan leaves aren't blocking them. Some cut them, which I don't suggest, or pen them down with paper clips. You also want to make sure you are getting good air movement under the screen once it starts to get jungle like down there or it can become too humid and cause mold and a play ground for pest. You can trim the undergrowth, but don't just hack every thing off, but make sure to get old leaves out of there fairly quick and you can clip all the bud sights down there because they will not be getting any light once the screen is full so they will just be taking production power from the main buds. Some place a little fan blowing under the screen once it becomes full above to promote air movement.
Make sure you have a method to be able to flush your plants, because remember you won't be carrying 6 plants with a screen to the sink to flush, and you want some water run off when watering IMO and you need to have a method to keep things clean.
Also, you don't have to pull all of the branches under the screen, you can tie them down to the screen. It is extremely hard trying to pull a branch back out of the screen when you find out that you didn't give some other branches, or new branches enough room and may have to start over lapping. This way you just un tie the branch if you need to reposition. Make sure that you follow some kind of pattern as well when laying, or tying down the branches, it will make it allot easier, like doing something like a twirling star pattern, or something to help you keep it organized.
Hope this helps some.
Adieu