I trim out the bottom of the plant (lollipopping) continuously until they stop stretching, then after week 5 or so I'll start removing remaining fan leaves to thin out the canopy a bit. If your plant is branchy it's a good idea to thin the number of colas that will be produced too, do this as they stretch or right after.
Lollipopping has many advantages... less to trim, bigger, higher quality colas, easier to water, better air circulation and better resistance to powdery mildew.