While the exact date is unconfirmed, it was approximately late August 1968 when the members of Led Zeppelin first entered a recording studio. A pre-existing session had John Paul Jones booked for P.J. Proby's album, Three Week Hero. Release date: April 1969.

John Paul Jones: "I was committed to doing all the arrangements for the album. As we were talking about rehearsing at the time, I thought it would be a handy source of income. I had to book a band anyway, so I thought I'd book everybody I knew." (C. Welch)