All the other advice is good- I'd only add this bit:
If you're mating 45* angles, which is how I read it, it's a good idea
to use biscuts or splines all along the joint. It'd save you a lot of
trouble when it comes to installing, especially if the tops of the
cabinets are out of plane at all.
If you have the option, you might want to rough cut it a little
oversized, and then sand down to your mark with a belt sander or use a
router to make the final pass. I've never chipped it with the router
or sander, but I've done it with a saw, even with the laminate blade.