They're not going to officially start marketing the next DLC when HotR hasn't even been released yet for console. (Though they did start the push for Morrowind before Homestead hit console, but I think that was a special case since Morrowind was their main marketing focus for the year and since Homestead was a non-DLC update.)
My bet would be on PAX West next weekend. Major convention event that happens after HotR's console release.