Variety reported that the production played three previews on Broadway before opening. The opening was on Saturday evening, November 18, 1961. Some online sources list November 16 as the date of the first preview, but that is almost surely incorrect. It is most unlikely that there would have been a preview matinee on Saturday, November 16, followed by the opening performance that evening. The first preview was most likely on Wednesday evening, November 15. It was not quite unheard of at this time for a show that opened on a Saturday evening to have a matinee preview that day, but when that heppened, it was because the opening was delayed, and a substantial number of tickets had been sold for the matinee (or perhaps even a theatre party). In the case of The Gay Life, there was no change in the opening date in the time leading up to the Broadway. The opening date of November 18 was set at least as early as mid-July 1961, as the date was mentioned in a New York Times theatre column on July 24.
Previews were often not advertised for Broadway shows at this time, partly because they were usually sold as theatre-party benefits.