I don't know, I remember Napster as being quite late to the party. Everyone I knew (geeks and some non geeks) had been happily using ratio FTPs for years (using usenet and irc to find them) and then later Audiogalaxy took care of the discovery problem. I also remember CD drives being fairly common by 1996/7 (it was CD burners that took a few years longer to hit sensible price points).
But its been a while so maybe my rose tinted glasses have munged things a bit! :)
And you're right, BBSes were doing similar things first (although I assume good ones were harder to find than usenet groups or irc chans - don't know because BBSes were before my time!) but of course the mp3 standard didn't exist back when they were at their zenith. MP3s only started appearing en-mass around 1997 I think (??). Before that, I remember every one used to share tiny wav and midi sound file clips on their homepages (my first ever homepage was made to share wav clips of simpsons and monty python dialogue - lol how embarassingly quaint!)