If it’s an auto strain, you can stay in a 18 or more light cycle. There‘s a reason why they are called autos and they love light for growing, even in the flowering stage. If you are doing photoperiod seeds, then leave them at 12/12 for flowering cause you could cause your plant to reveg. Don’t go by the schedule they list on the package, as they can go a few weeks longer. Get yourself a jewel loop or grab a cheap wifi digital microscope off Amazon to sync with your phone/tablet. Gonna be looking at your trichomes and looking for cloudy and a hint of amber to them. Look at them on the bud and don’t go by the ones on the leaves