IIRC, “son of a bitch” was first heard on the final episode of MASH, when Hawkeye says it to his shrink.
I think “son of a bitch” was heard on U.S. broadcast network television years before that. I’ll look for specifics.
Keep in mind that on Saturday Night Live, Gilda Radner’s character Miss Emily Litella would sometimes turn to Jane Curtin on “News Update” after Emily had been corrected by Jane, sweetly smile, and say, “Bitch.” And Gilda Radner left SNL in 1980, three years before the last episode of MASH*.
When was the first broadcast of True Grit? John Wayne says “son-of-a-bitch” in that movie, and I remember seeing it on TV sometime in my teen or preteen years. I kind of remember it being mildly shocking, at least in my household.
Actually I believe that he said it in an episode previous to that as well. He was working hard to save a N. Korean soldier from severe wounds only to have him taken away at the end of the film by S. Korean soldiers for an execution or something. As they were taking the N.K. soldier away he said “You son of a bitch” to the head S.K. soldier.