At least two rounds unless gets scuffed up. I used to play a ball for multiple rounds if not lost superstitiously saying its got good juju so let it play! Then saw My Golf Spy study on balls marked or scuffed even slightly and how much its performance dropped so now take out of play sooner.
I like to generally show up about an hour ahead. I go through some chipping and putting routines, then hit some wedges and irons on range. Just enough to get feel and tempo. Spend few minutes before going to tee think about the round, wind, etc.
I always chip and putt to get feel down for the day. Treat balls on range not as a practice but a warm up. Few wedges get loose and tempo down. Do few half iron shots to get feel and transition into full irons. Really just want to get loose and comfortable not beat balls trying to find or fix something.