| Although crepe myrtles are very hardy, they're getting ready to leaf out, which is probably the most vulnerable time. I wouldn't do any pruning right now unless it's absolutely necessary: If there are branches that cross or rub against each other or that smack your head when you get close to the crepe, then, yes, I'd take care of that. That kind of stuff you can do at any time. Have you heard of "crepe murder"? It's what crepe myrtle fanciers call the topping (chopping the tops off) of crepe myrtles. Although it's hideous, counter-productive, & destructive, some commercial landscape maintenance companies still do it to their clients' crepe myrtles...& get paid for doing it! Crepe murder destroys the natural shape & beauty of the plant & stimulates the crepe to produce many skinny twigs growing out of the stumps.
Very ugly. It makes me think of fingers growing out of someone's shoulders. (So don't do that!) I have a number of crepes, & I do minor "scissoring" whenever I notice a new shoot going in the wrong direction. | 
