SOG... outdoors? need help..

Hey guys, so my first grow was a success!.. I got about 10 ounces from 5 plants. Although 6 were from one plant.. we used miracle grow soil with that plant and native soil for all the others.. learned my lesson with that one!

The plan:
For this years grow i am planning on about total 50 female plants, between 3 or 4 different locations.
For this years grow i want to try a scrog type ordeal for an increase in yield.
So far my plan is to bury about 20 plants, in 7 gallon grow bags pretty close together.
One of my questions so far is when would i put the screen on the plants... when they start showing signs of flowering? or during the veg cycle.

In all my experience I've done much better spacing out plants and doing fewer. Since they are not restricted outside..let them get huge..and the buds will do the same! Not to mention that gives you many fewer plants as far a legality is conerned!! Also put them in the ground if possible-makes a BIG diffenence in size. (I know this doesn't answer your SOG questions) - Best of Luck!