Kitchen Reno… when to paint

We are going to start our kitchen Reno hopefully this early spring.We purchased used cabinets and will be using them plus a few extra pieces that will match the door. The pieces I found are unfinished (much cheaper that route), hence our reasoning to paint them all the same. Do my questions are: will the difference in finishes be seen after we use all in one paint and Is it best to paint the cabinets with all-in-one before or after they are installed?