As far as switching from veg to flower, in the past once I finally make it to my 6th internode or set of leaves/branches from the bottom, I have been successful. They will double in size so you need to consider you height and space requirements. Some sativas (in my opinion only) never 100% stop stretching. Mine was quick answer. Your in great hands with the others watching over you. Regardless of the equipment you have or do not have... get a decent (not cheapest) light timer for sure if you haven't got one already!!! Not the most expensive either but... And, watch your / watch out for light pollution during your dark cycle once you flip to 12/12. You want total black out darkness if you can help it during dark cycle with no peeking in there (by you) during said dark cycle..