I rushed a bunch of shows REALLY late this year, like between 1.5h and 10 minutes to curtain. But most of them had already given closing notice (Honeymoon, Heidi Chronicles, Zhivago). I rushed Gigi in early previews like 10 minutes before though and we still got 2 pretty good tickets.
That's why I think It Shoulda Been You should be possible shortly after 10!