Slackware was my first distro too, probably around 95 i think as I got a CDR copy from a friend in high school. It's certainly not been my daily driver for that whole period, but I think I've probably at least had a linux system operational for nearly 30 years.
I've been using Windows since maybe 92 and MacOS since 86. I think Solaris is the only other OS I've used a significant amount.