FIRST OFF . . .

The national Nielsen ratings average for Fox Broadcasting’s 3-week-old shows is 4.0, not exactly the 6.0 rating promised advertisers. However, Fox spokesman Michael Binkow says officials at the fledgling network are “thus far very pleased and encouraged by the numbers.” He said that the 6.0 rating promoted to advertisers (each national Nielsen point represents 874,000 TV homes) wasn’t an immediate figure but “an average over a long period of time. We’re not concerned with the ratings right off the box; we’re concerned with the likability of our programs and their long-term acceptance by viewers.” George C. Scott, starring in “Mr. President,” joins the lineup Sunday at 9 p.m., and Fox hopes that will help, especially with adult audiences. Johnny Carson, whose Carson Productions--with Gene Reynolds and Ed Weinberger--is producing the show, thinks it will. “I think we’ll be hard put to come up with any humor that’s funnier than what’s going on in the White House,” Carson quipped this week at a press conference. “But we’ll try.”