All your fan leaves are going to block a little light from lower buds don't worry about it. But if you have leaves that are directly over a bud trim it off, only trim one or two every three days and the plant will be ok. Other answer is let the plants form their own canopy and concentrate on the top buds, or Sea Of Green, which is popular these days.

pruning - http://www.overgrow.com/growfaq/t507
sog - http://www.overgrow.com/growfaq/826

peace