Help me, Help Them

All right so my little side project is progressing, but I have some concerns. I am working with a 4x4 flood table and a 1000 w hps. I just started from seed and have sprouted about 30 seeds (Norther Lights x Skunk, G13x budda, White Widow, Hindu Kush) I am worried about eventual over crowding i know that with my soil set up 10 plants Packed(more like over-packed) my 4x4 room so how will I keep the maybe 20 (I can dream can't I?) flowering females on one 4x4 table? the sprouts have come up from there rockwool cubes way faster than i have ever noticed in soil (like a day later) should I just start hitting them with the 12 on 12 off or veg them for like a week I just don't know how to judge how big they are going to get. (I will be growing in 4inx4in rockwool cubes) Thanks a ton

4x4 space you should be thinking of finishing with 16 plants max,, you should be able to get 16 5 gallon palis in yhat space. You will lose alot of your plants (males). Out of what you have left keep the best 16 females. Wait untill they are a foot tall before flowering. Take the clones before flowering (if you have a smaller room u can use as a clone room.