As long as you can make it dark in there when you want it to be dark, regardless of what time of day that actually is, it will work.
As the others have pointed out, it will have no effect on the plants. Reading up on many other msgs we would notice that some people will turn the lights off for 24 to 36 hours before starting the 12/12 schedule. Good chance that someone will ask something like that within the next two weeks. Some have written that they change the time the lights come on and then off by an hour a day until they get to the new "on time setting" as many as 10 days later.
If the plant is going to be a hermaphrodite then it would start showing the flowers for both sexes pretty much from the start. Usually what we see is a female plant starting to grow a few male flowers here and there on the plant towards the very end of the grow. It is doing this as a last ditch attempt to produce some seeds to perpetuate the specie. Yes, it is possible that some of those seeds could produce females plants that will start to form male flowers by about the 3rd week of flowering, usually mixed in with the female flowers that are under the canopy.
