A bunch of very little plants?

Now, how small can the pots start getting? I am wondering if growing like 20 plants straight into 12/12 would work, but in 1/2 - 1 gallon pots? Suggestions? Thanks, this is my first every grow... I have a 400w HPS & MH system on the way.

Right now I have 16 sprouts in those regular plastic party cups. Do you think I can have them all flower in slightly bigger cups?

I originally wanted to grow 10 plants in 1 gallons, sex them, and then put the remaining females in 5 gallons... and have 4 maximum (closet space!). But recently my florescents lighting my closet went out and I had to move them all outdoors to 12/12 or 11/13 light schedule! They're on my patio... but no-one can really tell they are weed by their size, no 3-5 bladed leaves yet. If I move them back onto 18/6 to finish the veg I am told will probably cause hermies... because I can't keep changing the schedule especially from 12/12 to 18/6, then back to 12/12 to flower in the near future.

Well, I found a thread when googling 12/12 from seed that was awesome.. the guy had his in these cups, and then put them in 1 gallons or 64 oz later. I have 10 1 gallon pots, and 16 sprouts going... I can sex them early because it's 12/12 from seed, and then put fems in the 1 gals and hope for 8+

Maybe even 18 or 20.. because these are all bagseed I don't know if they are for sure indica as everyone says. I will probably have an apartment inspection before they finish if they happen to be sativa, so those I will have to give to a friend as long he promised to give me a good quarter when it's finished .

And hermies I would kill as well.