The above SPECTRE 9 story, and another story in HOUSE OF MYSTERY 179, are both cover-dated March-April 1969. So both are his first published pro work, although I think HOUSE OF MYSTERY 179 slightly preceded the other on the stands by a week or two.

"The Man Who Murdered Himself" a 3-page story, is written by Marv Wolfman.

Another bonus with this link is the photo of a very young 20-year-old Berni Wrightson.