when doing it from seed you want a little bit of veg because the light for flowering may be too strong buddy... id let them get at least 5 inches high maybe 8 inches or you wont have anything for yeild buddy ul be pissed.... think of it this way. the longer u veg the more your going to get in reality. they need a good root system to really produce a good product. and when you turn them to flower they will double, maybe triple in size , so take this in to account for ur gro space.. and how much you want to yeild...... flowering a 1 inch plant you have half a gram harvest lol