I don't think Raven Software has enough resources to handle so many games at once. I'm pretty sure as soon as Quake 4 shipped, Wolfenstein went into full production which would have been at the end of 2005.
Look at the video, at X05 they already had people working on levels, character models and animation, so they've at least started full scale production a few months before that.
But I also happen to know that one of their character modelers has been working on the title for almost two years by now.