The buds for the following year are set on the new growth, after it blooms, then stay in place through the winter. That's why you cut right after bloom, so you don't cut off buds that are just about to open or cut off ones for the next year that have been set in summer-autumn.

I have several large camellias (approx. 10 yrs. in the ground, but already very large when planted) and I have never pruned them. They produce tons of blooms every year. I really don't see the need to prune unless maybe there's something wrong with the shape of your plant.