I've been experimenting with defoliation over the last couple grows and found the way that works for me: Top week 3 veg - Days 15-20 at 5th node. When it is ready to go to flower, at least 10 days to give her time to recover, I strip the lowest bud sites right before the 12/12 flip. During flower I let her go until week 3 (F16-21) and then I remove branches, bud sites, and fan leaves that are covering bud sites or aren't getting any light. Some plants will require more defoliation than others. My Kosher Sorbet needed very little, while the OG Kush I have been battling for the last 2 weeks. I also prefer to do my defoliation in 2 stages. 1st stage is to see how the plant responds and the 2nd is to remove anything I missed during the 1st defoliation. Plants that I don't defoliate have reduced yields because the light couldn't get to the lower bud sites and those turned into edible/concentrate. Smaller buds make trimming a lot more troublesome as well. Good luck and happy growing!! 💪