I agree with all above posts. I veg photos with my autos under 18/6, once my autos are about 2 weeks or so from finishing I'll flip my lights to 12/12 and let the photos start to flower. Usually by the time I harvest the autos about 3 weeks from flip the photo plants have already finished stretching and are starting to work on making buds.
While the photos veg they wont need much attention unless you plan to train or do anything technical to them. I have 5 photos in the room with 12 autos, my autos are still a good 4 -6 weeks out so in about 2 weeks I'll take a few clones to preserve my mothers then flip the lights a week later.