I think from 2003.
On Halloween that year, I dressed up as this character at work(cash register, Hobby Lobby), and I decided to put up a couple pictures of the fox for reference. Some people asked where my hat was, thinking that was part of the character's wardrobe. I had to tell them that he never wears that hat, except in this one drawing.
This is a lesson in choosing reference art to show what your character looks like. Choose a standard wardrobe.