They're not gonna penny pinch, they're going to start the huge marketing campaign probably somewhere around May, and it will be damn near constant until July 20th. Warner knows what they're doing. They're consistently one of the highest grossing studios every year for a reason. It will seep into the consciousness, but Warner isn't looking to have a 30 second ad and then have nothing to show for it until May when the film will actually be near completion. And you also don't want to want to hit peak hype too early either.
Worldwide, it would be downright shocking if TDKR does not hit 1 billion considering it will probably release in China this time around and more IMAX theaters contributing to gross. Also screen counts will have increased considerably since 2008. Domestically, I expect TDKR to fall considerably short of TDK, but worldwide gains will make up for it and then some. It's not that hard to hit a billion anymore as evidenced by the three films that were able to do it in 2011 (Transformers, Pirates, and Harry Potter)