where does the universal time code come from in the first place?

I'm finding it difficult to phrase this but if the universal time code was taken off of lars' ass, and lars is fry, and bender goes back in time to put the universal time code on fry's ass, then where did it come from originally? It has to have come from somewhere, because had the events of bender's big score not happened, it would've never been tattooed on fry's ass, but had it never been tattooed on fry's ass, the events of bender's big score wouldn't have happened.