while the article does not provide specific dates for the “prehistory” the Not Rocket Science piece refers to an automated integration system working circa 2000~2001:

> February 2 2014, 22:25 […] Thirteen years ago I worked at Cygnus/RedHat […] Ben, Frank, and possibly a few other folks on the team cooked up a system [with a] simple job: automatically maintain a repository of code that always passes all the tests.