Hello! Plants are looking good! I don't know the size of your tent, but I run a 2-plant scrog in a 3x3 tent and I put the screen 8" above the soil. Maybe 9" if I really need the space. I fear you will be quickly running out of room on this run. The horizontal LST should be going before you install the screen. The way I do it is to keep tucking the branches through the screen during veg until I have 1-2 squares at the front and back open, then I flip to 12/12. Don't forget about the flowering stretch for the first 2-3 weeks after you flip to 12/12. The plants are going to shoot as much as 40% of their current height, which is the reason to leave some space in the screen, so you can fill the screen and THEN let the plant grow up through the screen. The goal of the scrog is to have an even canopy with 5-8" of branches sticking up above the screen by the end of the flowering stretch. From there, I would recommend another major defol during the third week of flower to remove big fan leaves that block the bud sites. In your setup, it looks like three plants are going to crowd the screen and you will be out of space very quickly. I am on my 6th scrog run now and each time is different since plant genetics determine how much flowering stretch. I've had a plant stay close to screen height, while it's tent-mate shoots 12" above the screen. When I was first learning to scrog (I'm still learning), I read this tutorial and tried to follow it to the letter. It is a great method and if you stick to it, you will have an even canopy before you install the screen.
https://www.growweedeasy.com/scrog-tutorial
Have a look at a few of my diaries and you can see how two plants will fill the screen and still be manageable with great results! My suggestion for your setup is to get that tall corner plant moved forward toward the middle of the screen (middle as in front to back, not middle of the tent) and start tucking the branches into the surrounding squares. You could also lower the screen a bit and fill out as much of the screen as you can. If that makes the screen look pretty full, I'd say flip to flower immediately. For your next run, I'd highly recommend only 2 plants in 7-gallon fabric pots and see what you think.
Check out my Veg timelapse at the end of my 10th week at this link to get an idea how far the screen can be filled before flipping to 12/12:
growdiaries.com/diaries/20242-gorilla-zkittlez/week/104766
I hope this helps! Good luck!