Nah light placement has nothing to do with it. As long as you have enough light coverage and proper spacing you can acheive that.
You dont have to wait that long between snippings either. I dont go by set intervals or anything but I just snip a bunch let it recoop for a couple days and do it again till you reach the desired effect. You will need to do that in flower too. Snip all the nonproducing bud sites so it can concentrate on the main cola.
By rule of thumb (by me) cut the first six inches from stump up. It will help with circulation and get rid of Popcorn Bud Sites.