Long before there was Starwood, as a kid traveling with parents, probably a Sheraton in Eastern Canada at about age 5.

As a young adult, the earliest I can specifically remember would be a Sheraton in Philadelphia during my last year of graduate school. There may have been a Westin before that or a hotel that has since left Starwood. Apparently I had both Westin and Sheraton frequent sleeper cards before SPG was created.