Its really not hard to find information you know, these two topics where on the next few pages. Im sure there will be more if you can summon the energy to use the search function...
Some people say it's ok to do it now with how the genetics or whatever have advanced, others say stick to LST. I guess the best thing to do is start a few seeds and try it on one then compare the end results.
Topping might be too extreme.Stick to early fims and lst.You want to start early 3rd node or so,since the plant chooses when to flower you want your canopy "set" before flower.Once they start flowering you want to avoid as much stress as possible.This is what works for me.