When you order a gig and select the one day option, I am suggesting that this be within 24 hours, i.e. one day. One only selects this option if they need something quickly, so it is rather a pointless feature if it’s 24 hours plus whatever timezone you might be in according to your clock.
When you order a gig that has any number of days (including one) it starts a countdown timer that is really obvious. A one day gig starts a 24 hour timer as soon as the order begins. Time zones don’t affect it.