i had a separate veg chamber where i would veg clones for 6-8 weeks. i topped them once they had 4 nodes and continued topping and lst until they almost reached the size i wanted. then allow 2 weeks without topping for the plant to recuperate. at this point i would move them to the flower chamber and, as you said, push the screen onto them. i would leave the lighting on 18/6 until the screen was about 75% full then switch the lighting to 12/12. you must continue tying the branches to the screen for the 1st 2 weeks or so of 12/12 until they crown off and begin budding. then just watch them grow. imo it's ok to trim fan leaves above the screen that are shading budsites as lond as you do so sparingly. leave all fan leaves below the screen alone. alot will die and fall off on there own anyway. sorry i took so long to reply. good luck.