Oh now that's a good question. I'm thinking 1994, because of which radio station I was listening to and I wasn't sick of them yet... Now I wish I had a written note of it.
That sounds about right. Similar time to when I was seeing TV shows talk about to to reach them on CompuServe, AOL, then just straight up WWW websites. I especially remember my dad saying, "Well, it's definitely happening now if we're getting .com domains on regular TV ads." (He was using ARPANET as a teenager before going on to Stanford for EE and Physics, so he'd been following it for a while, haha.)
