Interesting. What I find most interesting, in going over that, is the location of Emerald Island, toward the southeast of Antagarich. Only because it's been said that Emerald is a tropical island, yet its location on maps seems to suggest that it's farther south than the tropics should be -- it looks to be near the frozen southern edge.
On the other hand, it could be in a warm ocean current, which does affect the climate IRL.
I'd say six or seven weeks would be a reasonable estimate.
PS...the map in that link you posted at Celestial Heavens is the same map that I'd found elsewhere and referred to.