The calendar of the discordians has 5 seasons, of 73 days each. Each week has 5 days. There are 5 Apostle holydays and 5 Season holydays, one per season. St. Tib's Day occurs once every 4 years.

Happily January 1 is the same day as Chaos 1, so one can easily map Julian dates to discordian dates. (1991 Julian = 3157 Discordian, the next St. Tibs Day is in 3158)