You won't see pre-flowers for a long time on those plants. Once they get a little older you can put them on 12/12 and in a week or two you should see pre-flowers. There are plenty of pictures online if you google "sexing cannabis" or "male female cannabis". Once the flowering stage is going you will easily be able to tell if it is male or female, don't worry about that.

If you put those plants outside now you will get very, very little harvest from any females. It is way too late. You should just grow those indoors until they are half as big as you want them to be when they finish, then put them on 12/12 (they could as much as double in size while flowering).