Actually, the Harry Potter play is similarly crazy in terms on pre-sale. I bought my ticket for March 2017 last October, a full year and a half in advance. Okay, it doesn't actually start performances until June so I guess they're "only" sold out for 6-9 months (vs. a year), but at the time no casting had been announced, and obviously there are zero reviews or word of mouth as this point, so it's just as crazy as Hamilton.
But I digress. Back to Hamilton everyone!