When I punched the walls for the POCR, I used one of those vibrating tools like the Sonocrafter. I marked the hole and then ran a long drywall screw into it as a hand-hold. I held on to the screw as I cut it out. That way the plug didn’t fall into the cavity so I could save it for when I needed to plug the holes. They are stacked in the staging closet for when I need them. Looking good so far!