I suspect they might start rehearsals in London (since Mendes is based there) and then move to NY, but just a guess.

This seems like an awfully long time for them to be apart if the rehearsals are in New York: first rehearsals (some of which will be in NY), then performances Jan-Feb. in NY, then touring, then finally back in London next summer. Meanwhile James is prepping for Wanted 2 Sept.-Oct., they film Nov.-Feb. Then--perhaps--he goes to NZ to film The Hobbit for the next year? Meanwhile, Nowhere Boy preems at London FF in October...and hopefully TLS will be screened as well...and her Fonteyn/Nureyev TV special airs in October (think I read that somewhere). She's going to be a busy woman! Sounds like it will take some careful coordinating for them to find some time together.