Laugh if you want, but I would say that my first step into jazz was listening to Spyro Gyra's Morning Dance on a Nautilus Super disc in a audio store on some Maggie speakers in 1979. I went out and bought the LP, not the speakers. I was still heavy into my rock phase at this time, Zepplin, Skynard, Floyd, etc.
Fast forward about 20 years later, and Miles Davis started developing my current tastes, where jazz is my prime genre of choice.
Cheers,
John