So did the roofer also mention that pulling panels off and putting them back on adds like $2000 to $3000 to the job on top of the new shingles? My neighbor did exactly what you're thinking, waited, and ended up paying a crew just to take the panels down and store them in his garage for a week. If your roof is 17 now and you're only doing a shed setup, maybe start there and let the house roof live out its last few years first. The shed is small enough that it barely matters either way.