In Earthdawn exist two different kinds of calendars, the Theran and the Throalic calendar. The Throalic calendar is divided into 12 month with 30 days each.
The months of the Throalic calendar are: Strassa, Veltom, Charassa, Rua, Mawag, Gahmil, Raquas, Sollus, Riag, Teayu, Borrum and Doddul.
On the opposite the Theran calendar has no months, they simply have numbers for their weeks, which include 5 days. In both calendars exist no weekdays.
For the Throalic calendar a date would for example look like this: 3rd Veltom 1510 TH
The same date would in the Theran calendar look like this: 7/3 1070 TE (7th week, 3rd day)
Several calendars have been made by Fans. I also made a Throalic calendar and a Theran calendar, if you should ever travel through other Theran provinces. Additionally I added the link to Red Brick's EPC appendices, wherein you'll also find a throalic calendar made by Red Brick.