its time to flower can i choose what 12 12 will be

so im about to go 12 12 but i want the lights to be on at night to act as heating cuz its outside in a tin shed and its cold at night. right now its off at 9 am and on at 3 pm could i make it 5-5 or 6-6 or 7-7 without screwing with there heads????? and makin'em grow balls

just leave em in the dark until your ready to start flower cycle...ive seen some people go with up to 48 hours of darkness before starting flower. i personally think thats a little too long but yeah you just leave em in the dark until whenever your ready to flip the lights on for their first 12 hours of light.

thanks thanks

I had four babies. A couple started to preflower, so i just turned it to 12/12. One turned out male, two started to flower, the other one i havent noticed anything at all with. I have had slight problem keeping it on 12/12 exactly all the time because of my setup. Im confused wonder if anyone could give me some advise on what to do about the dud, or whatever.