a few observations... 1st , 3x3x5 with 250 w mh. increase wattage to 400W you will have faster activity.
repot those plants into larger containers. ( they don't like that trust me )
there is a major difference that you can't see with the hps , its mostly the plant using a spectrum of light that favors flowering.
your plants in general will double in size after flowering..so , you decide when. ( 5' tent )
and yes..plants will respond to more light ( they like that too )