SOG method - input wanted

Ok soo basically ive done 3 grows and this 3rd grow all the plants got pollinated....they were from greehouse seeds and there pretty good ...however i got A LOT seeds and im thinking of growing using the SOG method but would like to know how fast will i be able to tell the difference between male/female because all these seeds i have arent feminized.
I dont want to have like a shit load of plants only to get a decent amount of females in there. So my question is do i use all these seeds or get feminized? Im looking to fit as many as i can under a 400w hps as well, anyone know the optimal amount that would work?
Your input is needed

first off a SoG needs clones to run properly, so if you want to use all of those seeds to produce one or 2 good mothers (and yes, it took me 50~ seeds to get amazing genetics for my mother....)

and second for a proper SoG your going to need another light for your veg room. you need a veg room and flowering room so you can have plants in veg AND flowering at all times, to allow you to harvest x# plants/week or every other week....... you should do alot more research into a sea of green before you start, i failed my first one due to lack of knowedge......

Edit: yea if you dont want 100~ plants i would say use clones. its 50/50 male/female so for a SoG lets go like this......... you start 100 seeds, 80 seedlings survive, 40 of them are male (at least 40...) now you have 30-45 left (dam males eh...)... so you then flower 3/week for 10 weeks so you get a 10 week harvest out of your little Sea-Of-Green. problem is, seeds are not reliable, what if their hermy? what if they dont germinate on time? what if they are just crap genetics?

i would just grow twice as many plants as you want to mature and pull the males at thier first show of male blooms. maybe transplant females to larger pots and enjoy a full harvast