Today still makes the most sense for announcement for Thursday Direct. And I expect it in an hour and a half.
But not gonna lie, hearing confirmation/buzz from a few other folks would inspire more confidence.
Cannot imagine Nintendo going til E3 or beyond without info. That would be grossly negligent on any companies part and they'd be roasted by everyone for it and rightly so.
There's really no way that I can see Nintendo waiting until E3 to do another Direct. Even if they don't have any first-party games to announce between now and June there will no-doubt be third parties who have some themselves and they won't want to be missing the Direct hype.