How long does it take for preflowers to form?

I did a search on pre-flowers and couldn't find any specific information on what i am looking for, so forgive me if this question has been asked repeatedly. I want to know about how long before pre-flowers begin to show, and will they show regardless of the photo period or do they have be under a 12/12 cycle?

Depends on the plants genetics, In general some plants will show pre-flowers after 1-2 months of vegging. Some won't show at all until it goes to 12/12 for a few weeks. Some will autoflower and there is nothing you can do to keep them from doing it.

Cover 1 branch of the plant with a black velvet bag for 12 hours dark/day, in a couple of weeks, just that branch will show you its sex.

It all depends bra.
I get them about 3 1/2-4th week in veg i can see da calyx n small white hair under a mag glass.

Sweet, and thanks for the quick responses.

you look like you could rip someone in half in your pic.