Robert Israel's answer shows it is misinformation to believe that the first mathematics to make page one of the New York Times was Andrew Wiles' proof of Fermat's Last Theorem (announced above the fold on June 24, 1993, as http://www.nytimes.com/1993/06/24/us/at-last-shout-of-eureka-in-age-old-math-mystery.html). It was widely said, but is not true.
What remains of my question, then, is to ask has any mathematics made page one of the NYT since the proof of FLT? I believe not, but I am no regular reader of the Times.
A garbled account of Khachiyan's ellipsoid algorithm for linear programming was on the first page of the New York Times on November 7, 1979 (below the fold).
Karmarkar's algorithm was above the fold on November 19, 1984.
See e.g. this talk by Margaret Wright.