MAX (on answering machine): Anyhow, as I sit here losing my faith in mankind, I wonder if we’re ever gonna actually go on that date we talked about many moons ago.
A “moon” is an old-fashioned way of saying “a month”, or one lunar cycle from new moon to new moon. Max is speaking poetically rather than literally – they made the date in October and it’s now November, so it’s only one moon ago, or at most, one moon and a bit.
The Annotated Gilmore Girls 