Rogue's first published appearance in the comic books was in Avenger's Annual #10 in July of 1981. But Rogue was actually created over two years earlier than that and was originally intended to make her debut appearance around July of 1979!

It was in this issue -- Ms. Marvel #24 -- that Rogue was intended to have made her first appearance.

The last regularly published Ms. Marvel issue was #23 and came out for April 1979. Although at least two more issues were already in production, the series was then cancelled. The completed #24 was later published in Marvel Super-Heroes for Summer 1992, and a part-completed #25 was distributed in Marvel Super-Heroes for Fall 1992.

The first 20 pages of #25 are by the original team, Claremont and Vosburg, with the remainder being finished off by another writer and artist.

The original cover shown for Ms. Marvel #24 reveals it was planned for release in June 1979. This means the series was probably at first intended to go quarterly rather than be completely cancelled. If #25 had appeared it would have been the September 1979 issue, but would have actually appeared in July 1979 (since comics always come out two months before their cover date).

Rogue appears in that original Ms. Marvel #25 - and in the Claremont/Vosburg material.

This means she was originally planned to appear in July 1979, although her actual first appearance was Avengers Annual #10, which came out two years later in 1981.