There is some misinformation online about when Broadway previews started for this production and how many there were. At least two major online sources list the date of the first preview as April 15, 1963, and they list the number of previews as 5. Some other online sources state that there were 58 Broadway previews.
The latter is clearly incorrect because the production's second pre-Broadway engagement opened in Philadelphia on February 27, 1963, and the show played there through March 16. There would not have been time between the closing in Philadelphia and the opening on Broadway, which was on April 19, for the production to have played 58 Broadway previews.
As for the listing of April 15 as the start of previews, we know that is incorrect because in the edition of the New York Times published on April 1, 1963, both an ad for the show and the show's listing in the ABCs make it clear that the show was already in previews. Unfortunately, it is difficult to definitively determine the start of Broadway previews because there had been a New York newspaper strike that started on December 7, 1962, and continued through March 31, 1963.
We list 36 previews, and we list the start of previews as March 19. Our source is an article titled "In and Out of Town" that appeared in the New York Times on April 14, 1963. In the article, critic Howard Taubman wrote of the many previews the production had played — "the musical expects to run up 36 at the Majestic by the time it opens." By that time the opening was finally definitvely set for April 19. If Taubman was correct about the number of previews, then previews would probably have started on March 19, given the performance schedule that the production played. This seems reasonable given the closing in Philadelphia on March 16, and also because some months earlier the production had announced a Broadway opening date of March 21. At the time it was still common for Broadway shows that had played out-of-town tryouts to play only one or two previews on Broadway before opening.
When the production finally opened on Broadway, no one was credited as either director or choreographer. At least during early Broadway previews, original director Morton Da Costa and original choreographer Onna White were both still listed in playbills. Da Costa's billing read "Entire Production Stage by Morton Da Costa." White's billing read "Dance and Musical Numbers Choreographed by Onna White."
At some point, Richard Quine, who had directed star Judy Holliday in several movies, came in to take over as director but, according to Ken Mandelbaum's book Not Since Carrie, he "quickly fled." Finally, Herbert Ross took over, uncredited, as director and choreographer.