FWIW (and I could be reading too much of this) - there was no mention in the big NY Times Fall preview of Back to the Future. I know, I know - it’s not opening in the fall. However, their theater listing article details shows out until next May - and no mention of it. There’s also a full page ad for Music Man with Hugh and Sutton…with no closing date indicated.
Cobbling together a guess from all this - I’d say it will be (at the earliest) June before we see BTTF, no matter where it lands (Winter Garden, the Broadway…or someplace else), even though tix are allegedly going on sale in October.