Hey, it's one of those threads where I think I can answer the question easily, but will only end up spawning a billion new contradictions! I love those!
1.) Everything that references a year number "1183" or "1184" is using the Northern calendar. The Southern calendar has a different year attached, but I have avoided using it to keep from confusing casual readers (e.g. anyone not posting on this thread).
2.) The Oracle is using the Southern calendar in his prediction to Roy. Meaning that the "seven weeks" Roy talks about is the time until the new New Year, exactly one year from the celebration seen back in Azure City.
3.) All other references are to relative time...no matter which calendar Redcloak uses, a year is a year, and during the Gobbotopia scenes he announced that it was six years until the one-year-anniversary of the battle. Since the battle took place about a week after the New Year, that means two weeks have passed since Roy's "seven weeks" comment--a few days to travel to Sandsedge, a week spent searching the desert, and a few days looking around the cities on the continent.
4.) The chart the deva shows should not be taken too literally. I didn't necessarily consult all possible references on how much time had passed when I drew it. I fudged it.
5.) Likewise, the "Eight months ago..." box in the bonus strip in Don't Split the Party is absolutely wrong; it should be more like ten months and some change. I think. I may still be getting it wrong.
There. Now you all have new fodder to point out new inconsistencies. BEGIN!