How are you going to know which plants produce the best buds unless you flower them all the way till done and test the actual buds? Take cuttings and flower the plants you took cuts from. When they show sex, remove males and male cuts. Keep the clones vegging in a separate area and flower the donor until done. Test the donor plants and select the best one. By then the clones vegging will be big and have lots of cutting sites, take more cuts and off you go with your SOG. Yeah that's a lotta friggin clones to fill 3 600's, should be a lotta weed when you're all done though. Just be careful of getting the plant count too high. Makes for a helluva sentencing if caught.