On a whim I went into the Creek directories on my PC and grabbed the oldest image I have.
This is from November 2006 and I successfully traced it back to an artist on DeviantArt who seems to have stopped posting there in 2012.
So here ya go. A 19 year old image of Craig and Tweek!
“Craig x Tweek colour” by stardroidjean.
I am going to make an assumption that this is way before the ‘ship name Creek even existed.
Artist: stardroidjean – https://www.deviantart.com/stardroidjean