typically i start off with 2weeks of 24 hours of constant light, from germination on. personally i think this keeps the soil warm and keeps moisture buildup from happenening and mold setting in early when the seedling is most vulnerable
after that its 18/6 untill im done vegging. you can veg a plant on this cycle for 12months if you want, as long as its not an auto-flowering strain
once ive vegged it out i switch to 12/12 untill trichromes turn milky
once ive scoped the trichromes i kick it back to 8/16
and when 80% of the trichromes have turned amber i give it 48 hours of uninterrupted darkness and then kill the bitch.
ive gotten some killer beer can sized buds from bagseed using this lighting schedule... matter of fact my profile pic is one of em