Stock dates. Hell, if you have been keeping up with the game then you would know that they still don't know what kind of MP to implement. Early 2013 is definitely not a reasonable time frame. My guess is summer or later.
Naughty Dog can do a lot with multiplayer over the span of a few months. Just look at how much they screwed up Uncharted 3's multiplayer from the June Beta to the October Beta.