The problem is that Confurence 0, the first furry convention to take place, already had a Furry Costuming track, so I'm assuming that the furry parties held by the Rowrbrazzle APA and the C/FO at San Diego Comic Con in 1985/86 were where furry costuming was first adopted as a fandom activity?
Anyway, thanks for any replies in advance. Someone else asked a similar question to alt.fan.furry in 2008 and couldn't get a definitive answer, but I'm primarily looking for general views from active and veteran fursuiters on how far back you all think it goes.
EDIT Relevant to this community: Any references from historical sources (fanzines, con reports, etc.) would be nice.
EDIT 2: I'm using this article as a jumping off point, much of which is derived from this article by Fred Patten.