Video Tape and the Jack Paar Tonight Show

when Jack Paar started on Tonight in July, 1957 the show was broadcast live 5 days a week.

video tape was introduced to tv in 1956, used a bit in 1957, and became commonplace in 1958. that was prime time. Paar's show was on late night and was a latecomer to video taped showings.

what was the date that Tonight with Jack Paar changed over to taped broadcasts?