Well, to be honest, I think your squares are a bit big. You want them small enough you can tuck a couple days growth into the next square, but big enough to not be a pain to work with.
Once you flip to flower, the plants will begin to stretch. Most strains will at least double in size over the next few weeks. You want to harness this stretch into your net. When you bend the branch over, the two growth tips at each exposed node will come up through the net and become new tops.
The trick is to time your flip to just fill the net as the stretch ends. Flip too early and your plants won’t have vegged enough (smaller root mass and less plant material to work with). Wait too long and your plants will overgrow the net. Which brings a bunch of environmental management problems like high humidity. Which in turn brings on bud rot, and powdery mildew.
I think that 8 plants in a 4x4 net is going to be a handful. Usually you would use less plants with a bit longer veg for a SCRoG. Say 4, maybe 5. Since you already have 8 very happy plants going (nice work), I recommend you just flower them out and use the net as a support only. Just let them grow up through the net, no bending. This will allow you to experience the entire life cycle of the plant. Then try SCRoG next run with fewer plants. Especially for your first time trying it. I’ve done it three times now and still haven’t got the timing perfect. I just think you will have less problems and more fun that way.
You will probably need a second net about a foot or so above the first if you just let them grow. Which is relatively easy to do.
Don’t worry, you won’t hurt them either way. After you’ve broken a branch, duct taped it back together, and a week later it’s fine. You realize it’s a pretty resilient plant lol.