Okay, lets break this into the several qs it is.
Sexing- 12/12 for 2 weeks should be more than enough time to sex your plants with confidence.
Putting them outside after- Nooo!!! Once they are flowering, if you put them outsied under ambient light, which is MORE than 12 hours in summer, they will take weeks to revert to veg growth, wasting all that time, then grow vegetatively until the summer ends, and then re-flower..... WITH HERMIES!!! because you stressed them by giving them irregular light.
So take CLONES and sex those instead, and leave your plants that are going oyutside eventually alone.
dig?