Your going to want to set the nets as soon as you can to keep the stalks low. If anything is important, its to feed through the trellis as its stretching during the first 2 weeks of flower.
I set my trellis late because I was waiting for my previous flower tent harvest to finish up.
I should have set mine a month before I did. but it worked out.
This canopy is about 5 feet off the ground.
Photo from 2 weeks ago
There are 3 nets holding everything up.