Billboard Pop Chart scholars often cite Bill Haley and The Comets "Rock Around The Clock" as the first rock 'n roll song - first released in 1954 and re-released in 1955.  Hence, most trades list '54 or '55 as the start of the rock era.  But, what came to be rock 'n roll probably drew it's origins in a song released four years earlier.

Rocket '88 -- a song by Ike Turner was recorded in the spring of 1951 - and came to rest at the top of the Billboard R&B Chart in June of that year.  Later successes by the aforementioned Haley - along with Elvis Presley, et al would obscure the start of the rock era.

This June will mark 60 years since Turner's Rocket 88 "rocked" the music world.