I have a mix of plants that I started growing at different times (just wanted to get the ball rolling). 3 plants are about 1.5 feet each between veg/flowering, the others are still little girls in the veg phase (about 6 in tall). I have the light on for 18 hr on/ 6 hr off. My question is, how will this affect the big girls who are definitely ready to go to 12/12? They haven't shown their sex yet and I suspect this is the reason.