Their sleep cycles tend to change as the year goes on. I've tried messing with the lights but it doesn't seem to make much difference to them. If you set the lights on a 12-14hr day like you have it, then they will sleep and wake according to what they need at a given time. The light timing itself has more to do with our schedules. They should wake up (lights on) an hour or so before breakfast feeding time and go to sleep (lights out) an hour or two after the last meal (in general). You can mess with the lighting a bit to try different combinations out to see what works best for you though.