The best time to prune a camellia shrub is right after it has stopped flowering, according to Gardening Know How. This is usually around May or June.
Camellia shrubs can be pruned for shape or for pest and disease control. SFGate states that camellia pruning stimulates new growth and that by pruning after the last bloom, the shrub's flowering for next year is not affected. Dead or broken branches can be pruned off the tree at any time to keep it healthy. Pruning yearly at a minimum can keep the shrub from getting lanky and too large.