Conversation so far:
What did Casey Kasem have to do with the American Top 40?
Kasem, along with Don Bustany, Tom Rounds, and Ron Jacobs, launched the weekly radio program American Top 40 (AT40).

Question: When did they launch the program?
Self-contained rewrite: When did Casey Kasem, along with Don Bustany, Tom Rounds, and Ron Jacobs, launch the weekly radio program?