YO

How would u know when to change to veg then to flower. is it posible to leave the light on threw veg then start droping light hours to flower at
12 12 .

As far as i know time isn't important you can set the lights to 12 12 whenever you want and no you don't have to do it gradually.

But if you want people to actually read your threads, try a better name than "YO". It's a great word and all plus you were probably stoned, but your not very likely to get a response with a title like that.

Peace
J