>Oops. Somebody made a mistake. It says previews start on January 21 on the marquee and January 24 on the window display. Whoopseeedoodles!<
I'm not sure anyone made a mistake. The accompanying text with the BroadwayWorld photo feature cites that Cinderella had to shift preview and opening dates by three days because Hurricane Sandy caused delays in the production schedule. The window piece is probably the only piece that has been updated with the new dates (or might have been produced later than the other front of house).
Press release copy:
>The new production of RODGERS + HAMMERSTEIN'S Cinderella will now open on Broadway on Sunday, February 24, 2013, with previews set to begin January 24. Originally scheduled to preview January 21 and open on February 21, the new preview/opening date results from a production schedule that was delayed as a result of Hurricane Sandy.<
Begin at the beginning and go on till you come to the end: then stop.