Need opinions on when to flower???

i am growing in a closet using a 3x3 flood and drain table under a 400 watt hps light i have 7 plants and i need to know when to flower them i dont want them to get over crowded and i want a decent yeild

pics nutes, age, height, what light cycle are u using how tall do you want them flower them at id say 1/3 to 1/2 the size u want