There is also this calendar.

There are a total of 550 days in a year.
The days of the week are
Arada, Torda, Lenda, Salda, Kenda, Zakda, Cosda, and Meda.

"In the early Set of Worlds, each world had their own method of keeping time. When the Circle was established, they created a standard clock which is now referred to as the Circle Standard Clock, CSC, or standard time. Any other time system used by the Worlds were to be called world times.
The Circle, placed in the World of Central Towers, calculated a Set 'year' based on the time it took for their world to move one degree in the coordinate system. However, as worlds do not move at the same speed, this information means nothing to the math required for teleportation."

Days are 24 hours long, and the Set does not use AM or PM, although local world times might.
Local worlds are also prone to differences in day length, hour counting, etc.