Linux: 1995, Sco (At work), then got a copy of Slackware on a Cover-CD around 2000. Shortly after found Debian and have been using that at home exclusively for over two decades, now onto desktops and laptops as well as a couple of home servers. (I use EL distros, Ubuntu and OpenSuse at work nowadays)
Longer history: 1981: ZX81. 1985, Dragon 32. 1988 Amstrad CPC. 1991 an XT. 1992 A 386 sx25 with 1mb ram, and so on.
Instead of you installing linux on them, why not make it a project for the kids? Give them a bunch of distros to try and see what they learn.