Jazz was created by African-Americans. It's impossible to say with any authority exactly where and how it started, other than to acknowledge that it started in Black-American culture. It is much easier to point out who was the first white person to play on a jazz recording.
Likewise, with “shout-out” and the hip-hop DJ culture of the late 70s and 80s, only black people ever used the slang phrase, until one intrepid white announcer used it on-air, and the rest is history. Who was that first white announcer and when? Probably in the mid to late 90s.
I'll settle for the first known use of the term in print; used in exactly the modern urban-hipster context.