Early ads for the production listed a Broadway opening date of February 29, 1972. Even a couple of weeks after the opening of the first pre-Broadway engagement, which started at the Kennedy Center Opera House in Washington, D.C., on January 17, 1972, that date was still appearing in ads. By the third week after the Kennedy Center opening, the date of the Broadway opening was changed to March 14, and another pre-Broadway engagement was added: two weeks at the Forrest Theatre in Philadelphia, which was to follow a two-week run at the O'Keefe Centre in Toronto that had always been part of the schedule. At some point, another pre-Broadway engagment was added: three weeks at the Shubert in Boston.
Eventually, the Broadway opening was re-scheduled for April 6, a Thursday, with previews starting with an evening performance on Wednesday, March 29. Surprisingly, even though the production was playing a Monday through Saturday schedule, there were two performances on Sunday that week (April 2), with no day off till the following Sunday.
As late as Monday, April 3, listings for the production in the theatre ABCs of New York newspapers still listed the opening as April 6, but by the following day, the opening was listed as being on Sunday, April 9.
Some online sources list a total of 14 Broadway previews, but with the two Sunday performances, the total seems to have been 15.