I read a few years ago that if you take two clones from the same mama and planted one in late April and one closer to the mid June summer solstice, the latter would be smaller, naturally, but finish earlier than the April planted one. It had to do with the early one going into full veg while the days were increasing in length, verse entering full veg as the days are constant in length and declining. I found some local strains I grew out a couple years ago that did seem to finish a couple or three weeks earlier, when I planted them late. I did it to keep them small and stealthy to be honest and the earlier flower time was a by product. Maybe.