I prune mine in the spring, just before the buds come out, only because
I enjoy the weather better then than in January.

The advice to prune "right after blooming" might be for something else.
Sometimes you can get them to bloom a second time in a season by
pruning the first set of blooms just after they fade.

BTW, they are called Crape (not Crate) Myrtles...

BTW, I forgot to ask. How far is everyone pruning these back?

Thanks,
David