There is no standard calendar for this world; each region uses its own. However, the easiest to convert to and from is the Feredar calendar, as it has the longest range--the two other societies with the wealth and power to perhaps instill a standard calendar on their entire dominion have ones with too short a span. The Islands restart their calendar whenever a new Lord or Lady is elected, and the City of Glass follows a dual-calendar system, one based on whether or not a new branch of the royal family has come into power, and a more practical, every-day one calculated from the date of the last King or Queen's accession. Heartwood, while having a long-range calendar (even longer than Feredar), lacks the reach to impose it on the rest of the world For the purposes of this timeline, I will use the Feredar calendar, which counts from the Magelord's Fall, calling each year since then a Free Year.
Later dates (after around 1050 FY) will also use the Imperial Calendar, which was the default for the Farglass Empire after the Unification.
( Timeline )