Quoc: To Tell the Truth was to have premiered on Tuesday, December 18, 1956, on CBS in prime time as Nothing But The Truth, but the program title was changed to To Tell the Truth the day before the show's debut. (There was one pilot episode titled "Nothing But The Truth", and the pilot / planned title, and the eventual title, both derive from the standard English court oath "to tell the truth, the whole truth, and nothing but the truth.") The series was recorded in New York City; initially at CBS-TV Studio 52, moving to Studio 50 late in its run. The existence of an audience ticket for a taping indicates that the show originated in color at the CBS Broadcast Center in late 1966.

Answer this question based on the passage: when did to tell the truth first air?
HW Chung: OK, some thoughts:
The important part for answering this question is: To Tell the Truth was to have premiered on Tuesday, December 18, 1956, on CBS in prime time as Nothing But The Truth, but the program title was changed to To Tell the Truth the day before the show's debut. The answer is December 18 , 1956.