I've had 2 occurrences of PMR. I was started at 20 mg prednisone for each occurrence and it took 3 and half years to taper off the first time and 1 and half years the second time around. Initially at 20 mg, my experience was all of the pain was gone but during my tapering off a little of the pain and some aches/stiffness would come back. It would normally go away after a few hours when I started moving around. I kept a daily log of my personal pain scale on a 1 to 10 rating with 10 being I can't take anymore. When I was tapering to the next lower level dose I would give it a day and see how I felt the next day. If my pain scale was a 1 or 2, I would stay at the new dose. If it was more and it felt like the pain was coming back, I either went back to the previous dose or tried splitting the difference and only bumping it up half of the amount I had previously reduced. My rheumatologist prescribed the 2.5 mg and 1 mg tablets of prednisone which made it easier to taper in smaller amounts and he encouraged me to listen to my body and my pain level. You may want to discuss it with your rheumatologist or doctor. Here's another discussion on the topic you might find helpful.

PMR Dosages and Managing Symptoms: https://connect.mayoclinic.org/discussion/pmr-dosages/
Tapering off of Prednisone: https://connect.mayoclinic.org/discussion/prednisone/