If the lower buds are not getting enough light then these are what you should trim. trimming the lower buds will put all the growth into the cola.
I trim fan leaves, but only right at the end, and then only if they are shading a bud somewhere. Maybe about 5 days before harvest. The tiny leaves off the colas are also capable of drawing in light. I do this too as it stresses the plant, and stress is good just before harvest. Even hit the bastards with 24 hour light the day before harvest, proper fuck their heads up.