Even earlier appearances of the phrase rock and roll appear in Billboard in the 1940's:
May 30, 1942 and "it's Sister Rosetta Tharpe for her rock and roll spiritual singing"
But Vaughan Monroe's band on June 27, 1942 is playing Coming Out Party "a riff tune in the rock and roll rhythm style"
But it's Count Basie (who's personal manager Milt Ebbins composed the aforesaid Coming Out Party) and his band on It's Sand, Man "wherein it displays its rock and roll capacities when tackling the righteous rhythms" in the October 3, 1942 issue:
More to come.