X-Men (Vol.2) #20, March 1993
Comics critics talk a lot about accessibility and the need for jumping-on points, but consider this: The first X-Men book I ever bought was about how there was a second Psylocke, claiming to be and looking like the original Betsy Braddock, and accusing the purple-bathing-suit-clad, Cyclops-seducing ninja of being an impostor.
Now, prior to this, my only experience with the X-Men was the cartoon, which did not feature Psylocke, at least not yet, and the Marvel Universe trading cards, which started in 1990, after the whole Lady Mandarin thing. I knew Psylocke’s first American appearance was New Mutants Annual #2 in 1986, but I didn’t know she was created in the Marvel U.K. books, nor did I know she originally looked like a white woman with pinkish hair who wore a baggy jumper. So this all confused the hell out of me, but it didn’t stop me from buying the next issue, or the one after that, or the one after that. In fact, I read both Uncanny X-Men and Adjectiveless X-Men straight through till Alan Davis took over in 1999, then picked it up again when Chris Claremont came back, then dropped it again once Grant Morrison left New X-Men and Chuck Austen switched books.
My point is, I didn’t let a silly thing like a story bogged down in continuity stop me from reading. If anything, it encouraged me to keep reading to understand what was going on and to seek out back issues dating to X-Men #1/Uncanny #281.