Factory reset on a Mac Mini, late 2012 running High Sierra

I’m trying to do a factory reset on my Mac Mini but I can’t cannot get into macOS Recovery by holding the command & R buttons at the same time no matter if I do it before, during or after the machine restart sound happens. When am I doing wrong. The mini is a late 2012 model running High Sierra. I’ve done this before on two different models of a MacBook with no problems.