when to flower?

hey guys! when do you start the flowering stage? is 4 weeks old ok? thanks!

If you're growing indoors:

Estimate the final height you want
Veg to 1/3 final height
Plant grows the leftover 2/3 during flowering.

what if your plant is 12" tall and the other is 8"? however their at 4 weeks? can it happen?

Of course it can. You can even grow plants 12/12 from seed.

thanks dude! + rep!