last time I did that on 2007 Altima (assuming caliper is removed and sits on the bench):
- clean from the dirt with wire brush and compressed air
- remove/clean sliding pins, clean with brake cleaner
- put a piece of wood where brake pads used to be
- use compressor to pop the piston
- remove boot and piston o-ring
- clean with brake cleaner and no-lint rug
- new o-ring comes in with a little bit of silicone grease
- attach boot on piston, slide in, attach retainer
- grease sliding pins, attach boots, slide in
- DONE
I assume calipers are not seized or damaged
remove / reattach / bleed brakes - these operations are the same if you replace calipers or remanufacture them, so I do not count them in “minutes”