Are you interested in seeing the regular IASW or the IASW Holiday version?
Here's what I am pretty sure will happen (and stay tuned to our
Disneyland at Christmas Time Superthread for any breaking news and discussion on the season as it happens, IF it's a DLR holiday trip you want to have!

):
IASW will, indeed, shut down at the end of October for the overlay. This year, I am guessing it will be down by 10/24 (Monday).
The holiday season officially begins this year on Monday, November 14th. Yes, a Monday! (We were all quite surprised about this Monday opening over in the Superthread, as the holiday seasons always officially start on Fridays.) The official start date is when all the holiday entertainment and IASW Holiday are officially set to begin. IASW Holiday has been known to have soft openings ahead of schedule in the past, though, so I would not rule out that possibility.
Because the official season start date is on a Monday this year, we're pretty much almost banking on the fact that IASW Holiday will be soft opening in the weekend leading up to it, capitalizing on those Veterans Day weekend crowds. The 2 parks will already be decorated right before 11/14, so having an official start date is just sort of a benchmark for when to begin the entertainment. If IASW Holiday is all ready go before 11/14, DLR will probably start running it ahead of schedule.
My guess is that IASW Holiday will begin soft opening on at least Friday, 11/11/11, if not Thursday, 11/10/11. And I am almost positive it will be running intermittently on 11/12 and 11/13, then in full swing on 11/14.
So if you make it to DLR by that Veterans Day weekend, I'm pretty sure you will be able to catch IASW Holiday. If you're not actually there on 11/14, you will miss a lot of other things that will not have begun yet, but IASW Holiday I think you'll see.
One other thing, just for reference - the 3 DLR hotels and DTD don't really get into the holiday swing (such as the very special GCH lobby, which is wonderful during the season) until right after Thanksgiving.