NBC’s promotional push for its brand-new morning experiment, as seen in a two-page ad in Broadcasting, January 7, 1952. (Trivia: Today had been scheduled for a January 7 debut, but in December 1951 it was decided to bump the debut back one week; among other things, it allowed a little more time to get everything ready in the RCA Exhibition Hall, plus it allowed a few more run-throughs before the big day.)
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I would think the first page of the ad (the top page here) also appeared in magazines aimed at viewers to urge them to tune-in.