Pruning is best done for most plants in late winter
I’m often asked when the right time to prune is. The answer depends on the plant. Most things that bloom in the spring should be pruned right after they bloom. Many are already filled with their buds, removing them would also remove next season’s flowers.
Deadwood can come off at anytime.
Here’s an interesting link that explains other reasons to hold off on pruning until the end of the season.