My family used to watch the Carol Burnett Show on Saturday nights. I can remember the opening to MASH always starting right after it. But I never watched MASH until around 1981 or so.

This is just by memory so anyone out there with definitive info please comment, but I beleive Saturdays on CBS had Mary Tyler Moore, Bob Newhart, All in the Family, MASH, and then the anchor show was The Carol Burnett Show for a full hour to cap off the prime time schedule.