I'm writing documentation for a computer script I wrote. I'm wondering which I should say:

  1. The script should run at the 1st of every month.

  2. The script should run on the 1st of every month.

  • 1
    On is used with specific days and dates, at with times, in with timespans (centuries, years, months) – StoneyB on hiatus Apr 8 '14 at 18:14
  • 2
    I believe this question provides the answer you seek. “At” would be used for an exact time (8:30 am on that day, for example), “on” is used when referring to the day in general (as in your case). – Tyler James Young Apr 8 '14 at 18:15
  • @Tyler - That said, we'd use at for a more general day, too: "The script should run at the beginning of every month." – J.R. Apr 8 '14 at 21:28