3 1/2 Weeks into grow when should i flower!!! My Sec grow too

So I have 10 plants growing in my closet. I'm using a 400 watts MH. They are growing lovely and fast at 3 1/2 weeks. I measured them and all of them are just about 12ins probably one more week. My first grow I veged for 2 months and she was huge only one plant tho. Now I have 10 hoping that i get at least 3-4 females but I think I my have more girls then boys (Hope) but should I flower at 12in and should I transplant after I sex them they are in 2 gallon pots one in a 1.5 or before, cause I want to kill the males then transplant soon after asap for space. Will I still get a nice yield flowering at 12ins. pics below closet is 5x3 and a half. but if I change it around a little I can get 5x4 and a half. what does it look like please comment people

No comments come on!!!!!!!!!!!!!!!!1

Everything looks nice and green and healthy. Flowering is your option, depending on height issues, space for side growth, lots of factors. Lots of people force flower at 4 weeks or so. Some, like myself, veg for at least 12 weeks and let the plants mature naturally as opposed to forcing it. That choice is on you.
Transplanting can be done anytime if you do it carefully, but better on veg, or at least early flower.If you plan on forcing flower at only 12 inches or so, you can use the two gallon pots no problem. Nice setup,looks good.

Let them grow! They look like they could veg for another couple weeks

ok thanks!!!!!!!!!!!!!

wait till you get preflowers is ultimately for the best, which is usually about 18+ inches or more in height if you do not train, ultimately it depends on your space restrictions.