Unless it is too big for the space it is in why prune at all? Now is not a god time or you will lose the flowers - autumn if you must.

Camellias will re-grow after quite severe pruning, but do this after flowering.( We have done this at Standen to rejuvenate overgrown plants). Then cut out what isn't needed, even down to a foot from the ground if needed. Don't expect flowers from the new wood for 2 years or so. If the plant is not outgrowing it's space, just trim back the tips after flowering if you like. Otherwise, they don't usually need pruning.