I wouldn't be surprised if we get a lot more new info at Pax East which is at the end of the week.
According to the blog, Thimbleweed Park was doing voiceover in January and came out at the end of March. Of course, that game involved several different voice actors recording the same lines because you were playing multiple characters, so we might actually be closer to release if we assume that Guybrush still gets the most lines. Then again, we also don't know how big the game is (I'm hoping it's a decent size, we already know of 4 locations: The Carnival, Melee Island, Monkey Island and a new island where it snows) , so there are a few things to factor in there. I hope it comes out soon though, I'm dying to play it!