I would expect IASW to close on January 20 for overlay removal. This is simply a prediction based on past practice; there is no official January refurb list yet.
Grizzly ended up having a late refurb this year, but January is the more traditional time, so I agree that would be a likely one as well.
Also, based on what's been going on the past couple years and knowing that the 60th anniversary is coming up, it wouldn't surprise me to see at least a couple of rides in each park down at that time.