As you can see from the first 2 response this is a sticky subject amongst growers on what to do. I know a lot of growers that say do not do it and a lot that swear by it. I've done both and find trimming can help to increase buding locations on the plant on a most strains. There are some i found that it stressed the plant out and decreased production for awhile and some that it did nothing to. Best thing to do is see what works best for you but the one thing I can say is that if you do want to trim wait tell day 14-15 of flower before you do it. Veg stage is for FIMin, topping and LST and other techniques. Hope this helps.