Ever notice in your nutrient feed cycles they show three-week veg cycles? I would always go more believing the results would be better.
As of late, I have changed my ways for several reasons. For one, I’m growing in hydro, and three weeks from seed can get pretty impressive. Secondly, time – especially with Sativas that will take longer in flowering, you may as well get the process started. But the last reason is I’ve learned that most indoor light does not penetrate much beyond three feet.
So rather than expend time and energy growing a canopy that gets lollipopped just pull the switch at three weeks and watch the results.