Surprisingly this comes up more then you'd think, for instance in Ancient Rome, tomorrow is two days away so all the dates are off by one from what you'd think it was. They mainly count down and it goes, 5, 4, 3, day before, day.

I noticed that when I read Tom Holland's new translation of The Lives of the Caesars. All the dates were in the form "N days before Kalends/Ides".