I decided to do a simple calendar just for ease of time passage bookeeping. It is based directly off the modern Gregorian calendar, but since Amber is the Pole of Order, they don't have the annoying problem of having to add days and minutes here and there to make sure the calendar fits to the passage of time. There is variation, as the length of days increases and decreases threoughout the year, but it balances itself out.
The Amberian calendar consists of 12 thirty day months, and each of those consist of 5 six-day weeks. The new year in Amber starts in the early spring, in conjunction with the first new growth after winter and the planting of that year's crops. This calendar is used throughout the Golden Circle, and even some of the closest non-aligned Shadows.
Anril (April) 1 is the first day of the new year, and kicks off the holy month devoted to the Unicorn. This time of thanks and celebration is not well practiced by the Royal Family, though Princess Flora annually throws the Spring Ball on the new year's eve.