I wonder the same thing.. I have been doing ALOT of research on this topic, and i have heard numerous different answers. none of them are the right answer either might i add.
I have heard that the smallest amount of light leaking into your room will ruin everything. (even a tiny led light on a power strip was reported to have ruined someones flowers)
Then again, some of my buddies will enter inside their grow room when the lights are running at 12/12 and will even use a flash light to find there way around once they enter.
I really do believe there is no correct answer to this discussion, because all plants have different genetics, and are all grown under different conditions.
The one thing i do know, is stress is the number one reason for a plant to hermaphrodite. The less stress, the more likely you are to have a female.
Ill keep my fingers crossed for you though, I truly hope all goes well for you.
Im going through the same stress right now.. i had a light leak the first 3 days of my flower. everything is sealed up now and 100% dark, but there is still a chance that my flowers might be ruined.. hopefully i am just over thinking, and being paranoid.