Day was born in Las Vegas, Nevada, and later moved to Downey, California.[1] He started acting at age six and after auditioning with his sister, was a Mouseketeer for the first two seasons of The Mickey Mouse Club in 1955–1957.[1][3][4] He came out as gay to his family and moved to San Francisco when he turned 18,[3] telling a Rolling Stone interviewer in 1971 that he was bisexual[1] and used drugs.[5]