I personally do very little defoliation at any point in the grow. I only remove an occasional fan that's blocking bud sites but that's about it.
But if your inclined to prune or defoliate I would do it after the stretch and keep it to a minimum to avoid stunt.
I prune off most of the popcorn producing buds and spindly branches and most branches that are coming off other branches. I will leave their leaves on under that. Plant still gets food and the energy goes into the buds you want to keep.
I flatten the canopy as much as possible and then remove budsites that won’t get light. I leave as many leaves on as I can, as long as I can. That’s food storage for later, and it also slows the progression of issues in late flower.