Man, I wish this was something that I could do with just keeping track of fulls and darks, because there are calendars for that, and even ordinary mundane paper calendars often have them marked.

But noooooo, I have to have a religion that wants "13 days after the full moon" or "the first dark moon after 137 days, 18 hours, 17 minutes, and 50 seconds after the vernal equinox."