In zone 5 I'd hold off longer.

tj

Will do.

Thanks!

Hold off until Mother's day.

Due to Pistachio's low height (it's a GREAT accent plant) it shouldn't need much trimming for shape, although each year with age the hydrangea will select a few stems to "ax", which will turn white and dry up. You should 100% be able to see which ones I'm talking about by the dates ^they said, although eventually you might develop a more trained eye that can spot them sooner.