Yeah, unless I find something earlier, "originated in dcu fandom, earliest recorded usage by petra and jamjar", etc, will probably be what I go with.

And, okay, if #dcu was through squidge, that tells me a lot more than I knew about what sort of fandom it was drawing from! So the term probably originated in the slash/lj/s_d/media fandom sort of comics fandom, anyway. (With comics fandom one can never assume.)