The roots of rock'n roll are complicated and varied. Ike Turner's "Rocket 88" is often cited - as in the post above - but it's one of many of its style. If you listen to the output of Syd Nathan's King Records which started up in 1943, there's a whole load of booting stuff there. Louis Jordan and Big Joe Turner and countless others all contributed.

Alan Freed may have used the term in his shows, but it was used earlier in song lyrics well before he "coined" it.