xtv out at least by September 16, 1997 (on Sun) (Score 1)

From a changelog on Debian packages,
http://packages.debian.org/changelogs/pool/main/x/xtv/xtv_1.1-10/changelog
comes the following for an early release of xtv,
    xtv (1.1-1) unstable; urgency=low
      * Initial Release.
      -- Jay Kominek Tue, 16 Sep 1997 17:14:36 -0400

I remember using xtv to view (and interact, as I recall) with others' X11 displays.
We probably installed this open source software from a third party's 8mm tape.