On January 12 1965
Jan. 12, 1965: The NCAA adopts the 1.600 rule for initial academic eligibility, which meant incoming student-athletes had to have a high school GPA and test scores that predicted they would have at least a 1.6 GPA in college.
Sources:
Sources: “In the Arena: The NCAA’s First Century” by Joseph N. Crowley, NCAA News and Champion magazine archives, the NCAA Media Center, and NCAA record books