That's very misleading then..
Why would they say that it's harvest Time then..
It says 63 to 70 days until harvest.
That wouldn't give you any indication about how long to leave it in the veg state.
Just how long should you leave Purple Haze in it's vegetative state?
I mean isn't there a normal cycle for the plant when it's out in the sun?
Cuz if that's the case I would like to achieve the best yields possible and let it grow the way that it was genetically designed to grow.
I know that Photoperiods rely on the light change and other factors, but
What's a good time to switch to
They say that harvest time because it sounds better than the reality of 2-3weeks longer that a home grower with inferior equipment would get. The breeder had a room full of plants under a different light and God knows what kind of nutes pumped in however many times a day... maybe one was ready for harvest in 63 days, then a different one perhaps tested the highest at 26% and maybe some others turned purple....so the breeder posts a pic and says done in 63 days with 26% and wow they are purple. This is called marketing. Think of hamburger commercials....
You leave it in its veg state as long as you wish to get the desired height, shape and health before flipping to flower whenever you feel like it.
To get the best yields possible you should grow just one plant under that light and train it out flat to fit in the footprint of that light. This is how indoor growers get more out of a plant that is designed to grow with apical dominance.
Alot of people are in here trying to help you get the best results possible....people who grow, not just people who read about growing.
Good luck