i like to use worm castings in the soil(alot) and then use 2 diff types of bat guano one is peruvian seabird(high in nitrogen and the other high in phospherus(i prob didnt spell that right........ as far as when to flower let the roots take off you'll see ur plant grow alot!!!!! then u know its time to through ur girls in to flower, also space is an issue... so just play with it and find out. i like mine two get about a foot to a foot and 1/2 and by the time thier done thier about 4 foot to 4 and a half. how many watts r u usin and how much room for flower

good luck man.... i just harvested last week and mmmm soooooooo goooooddd