in a 12x12 grow room with 12 plants, thats 12 sq feet per plant.
If you're in soil, you might be able to get away with that.
Look at heath robinson, though.
He uses that amount of space to grow like 4 plants.
You can do 12, just use your judgement on when to put them in to flower, dont let the 8 weeks veg necessarily be set in stone