I'm pretty sure I figured out about the concept of emulation and simulation from an early 90s Reader's Digest book I picked up in a thrift store when I was in middle school. It had some pretty interesting stuff related to computers and electronics in it, from the old sweaty robot thing called Manny the military built (for testing web gear and other clothing, apparently) to an article about the then-potential future of cybernetic augmentation (which suggested using compound eyes like that of an insect to compensate for the lack of resolution on digital cameras at the time, and mentioned non-cybernetic implants and prosthetics that were already common at the time), as well as an article discussing emulation and simulation, and it's use in software and hardware engineering at the time.
A little later I got a bunch of Game Developer Magazines from my uncle, and one of them had an article discussing the retrocomputing scene as it stood in early '08 (IIRC, it might have been earlier than that). It mentioned a lot of the homegrown hardware that was coming out for old 8-bit computers at the time, as well as mentioning emulation in passing. Soon, I think I downloaded ePSXe and some games over the course of a few days (I still had dial-up, and I'm pretty sure that this was one of the last things I used it for before I got modern WiFi) primarily Spyro and the Medal of Honor games. I think the first game I booted was MoH: Underground, and I immediately cheated to get to the weird secret level I'd heard about.