Stealth Box Grow (need flowering advice)

Dont quite remember the date I put these in soil but i wanna say the beginning of may.

Anyways these guys are getting up there in size and was wondering if I wanted to flower these in the same box they are in (see pic) when should i sex them and start flowering them? In other words i wanna do it soon enough so they dont get too large for the box.

http://i4.photobucket.com/albums/y14...1231/hiiii.jpg

They are currently on 18-6 light cycle and i'm using 4 6500k 42w CFL's and a 5000k 42w CFL.

I have another house located about an hr away that I have two seperate rooms set up for flowering and vegging, the veg room is just a bit full atm and just was kinda wondering what kind of yield i could get from flowering in this same box.

I'd obviously have to get 4-5 2700k CFL's and switch them to 12-12.

What do you guys think? I can provide more pics if needed.

Well it's a rule of thumb that for best results, you double the lighting from veg to flower.
If you have 5 6500k bulbs in there you would need 10 2700k for flowering or just add 5 more 2700k to your 5 6500k, for full specturm, which is the best route to take. Plants do better with full spectrum.