Hi Pmui,
You are in Zone6, so probably like me in Zone7, your main target are the brebas.
If you top now, those branches will not make brebas next year.
Now if those trees are still young and at the forming stage, then pinch.
But I would do something else: I would wait to have 10 cm to remove, cut the 10 cm sticks, and put those sticks in water for a month and then plant them in compost.
This year, I made 3 new "dalmatie" this way. If you don't want more trees nor future cuttings... Just pinch now or when you want.