Marge says that the event takes place on Friday the 13th in March (which she and Homer refer to as Smarch). Considering this episode was aired in 1995, the most logical time for the events of the episode would have to be either 1987 or 1992 as those were the only closest years at the time that March 13th would fall on a Friday. 1987 would make sense because Maggie (who was born around 1989) wasn't present at the meeting with Homer and Marge.