Hi and welcome to ILGM forum. Best place ever to get friendly and helpful info.
U sound like a new grower and I don’t want to confuse u with other people’s experiments. So straight forward info is:
2 types of plants.
Autoflowering who don’t care what u do with lights they will do what they want and flower when they want. People usually keep them on a consistent schedule Bc they do not like being stressed with random light schedules or transplants
Photoperiod plants. These plants will stay in their veg stage until u switch your lights to 12/12. Once u switch to flower u need to keep their schedule VERY consistent. Lights on and off at the same time every day. Best advice. GET A TIMER
Experienced growers like to try different things on their plants and that is fine. If something goes awry they usually have the knowledge to fix it. On your first grow I would suggest sticking to the “rules” of growing so u can get the feel for it.
Do u have any pics of your plants. That usually helps people here to help u.
Thanks and welcome again. It will b a much easier process for u if U join the forum and let some of the very experienced and knowledgeable growers help u thru it.