Dormant sprays need to cover the entire surface. So are often applied after trimming for economical reasons. But "often" does not mean "always". There are many reasons to apply a dormant spray before trimming, and many depend on the pests one may want to deal with.
And that means that different pests (fungal, insects, mites etc), can mean different sprays (copper, sulfur, oils, etc), at different times. So the answer may be, but is not always, simple or singular. It will depend on what pest you are spraying for and your local conditions.
I typically recommend one contact their local University or Ag extension for what is suggested for their area, and for the pest they want to control. As dormant spray schedules and sprays suggested can vary across regions.