I've also found visiting https://calendar.google.com/calendar/b/1/r/settings https://calendar.google.com/calendar/b/1/r/settings and setting date format there

I've also found visiting https://calendar.google.com/calendar/b/1/r/settings https://calendar.google.com/calendar/b/1/r/settings and setting date format there useful. Not sure if it's a universal setting like the previous, though.