"Connect the ground wire from the branch circuit to the ground screw"?
That's an excellent question and it can be quite confusing.
If you're using a plastic box, it won't have a ground screw, just connect the two ground wires together.
If you're using a metal box, there will be a ground screw. In this case, your idea will work just fine.
You could also wire a &quot;pig-tail&quot;. That would be the ground wire coming in with the rest of the power supply cable, the ground wire from the fixture, and an extra piece of bare ground wire all held together with a wire nut. Then, the other end of the extra wire goes to the ground screw.
Either way you choose to connect to the ground screw, be sure you wrap the wire around the screw clockwise so that the wire gets pulled into the screw as you tighten the screw. If you wrap it counterclockwise, it will get pushed out from under the screw as it tightens.