Okay, I posed the question on the Enthusiasts group, and member
Dave came up with an answer as close as I figure we will ever get. Looks like the change happened between March 2000, and October 2001 based on these boxes.
You can also see the October box is 'Revision C', so unless we find a Revision B box, I think it's safe to assume this date range. Like I thought, it was early on. Also of note, the logo went from a regular Trademark, to a Registered Trademark.
Hmmm, one more thing I need to go an document with all my boxes.