Different folks do things differently, but here's what worked for me.
The binding should be scraped level top and sides and the body sanded before you start any finish work, including sealers/primers/colors/clears. Then, you seal/prime with clear, skip the primer, mask the binding, shoot the color, remove the mask, scrape the color, and start shooting clear coats. Once you get to a point where you won't hit the color coat, start sanding between each clear coat. It'll eventually even out.
When you remove the mask, which should be about an hour after shooting the color coat(s), be prepared to scrape right away. The paint will be dry to the touch, but still soft enough that it's easy to scrape without chipping.
There are several different ways binding is scraped, depending on how often you do it. I've heard of pros and factory types who can do it freehand, they're so good at it. But, for the rest of us, a tool is a handy thing to keep us honest. You might want to
review this thread so see how I did the L5S in my sig.