Early flowering

I live in NorCal. Sunrise 6:40 am Sunset 7:36pm. 12 plus hours of light, why has my plant been flowering for about 3 weeks? Is it because the decreasing daylight triggers it? I have only grown inside and used 12/12 and could grown a long time and never saw a flower until 12/12, so I don't think it's just flowering because it's mature like some folks say....

Im still at about 14 hrs of daylight and my plants are about 2 to 3 weeks from bein done ! Things are different outside !

Under 14 hours of light most plants will flower.