Harriet was apparently very happy with how this was handled last year (she hates spoilers), so there's little reason to believe they'll change much the plans for TOM.

Beside the people likely to be "early readers" that Harriet has met in person and sent a manuscript too (this was done shortly after the manuscript went to Tor last year, by the way - and it's likely to be the WOT webmasters again, Jason and co.) they'll probably send review copies (not ARCs, there's no ARCs on the schedule they're on) fairly late in the game, and probably ask for reviewers not to publish anything before the release date. Last year they were not keen on sending advanced copies to anyone they were not sure would respect the embargo and only the sites they had dealt with a lot and trusted got the book a few days in advance. The rest of the complimentary copies/reviews copies got sent overnight the day before release.

That's my guess anyway. I really doubt it's gonna be any different from last year, as not only Harriet but all fans who hate spoilers and the people at Tor were very happy with the lack of "uncontrolled" advanced reviews that reveal too much. Tor gave us more free chapters to keep the hype going instead, and I think it was a lot more fun then getting reviews you can't really trust anyway and that can taint first experience of the book.