I'll believe a date when I see it on Jim's page, or it's announced by the publisher. Until then, the dates being put up are pretty meaningless. Personally, given that the book was just finished, I'd say that the Jan date is laughable, and I wouldn't be completely surprised if the actual date is closer to the July one than the Jan one. Late March, early April is probably the most realistic time period.
Until then, well, read something else
.