Walter Koenig's bid to join Star Trek: The Next Generation 's writers' room must have come around 1987, perhaps during production of season 1, which was after Star Trek IV: The Voyage Home in 1986.

Star Trek: The Original Series star Walter Koenig made a vocal cameo as Anton Chekov, ... I said, 'Come to my house,' so they did, three or four people: a cameraman, sound engineer, ...