Just to add my two pence worth.
If this follows any other major release, the shops will put it on the shelves as soon as they get it, they do not sit on stock of new games.
My experience of this was with FM2009 last October. People started being able to buy the game in shops at least 5 days before the official release date, however, the DRM servers did not go live until the official release date. Boy was there a lot of anger and pain on that forum (especailly as the DRM itself was a disaster as well

. Most people could not get the game working until 48 hours after the official release date.
Many thanks to Paradox for not going down the DRM route.