Tracy Austin came to town to promote the Colgate Series championships of women's tennis and with this youngest sports millionaire yesterday came another jarring reminder of time's flight.

By the time the rich event at Capital Centre rolls around Jan. 7-12, they might be calling Austin "the old lady." The next time she lifts a racket in competition she will be 18. Her birthday is Dec. 12, and her final tuneup for the eight-player showdown will be in Tucson Dec. 15-21.

Meanwhile, close up, the pride of Rolling Hills (Calif.) High's senior class looked like a million dollars as she met the media at the White Flint Bloomingdale's, and as for no longer qualifying as youngest player on the big-time circuit, commented, "I think it's nice. . .to move on to the next stage."

Qualifiers for the $250,000 windup to the yearlong Colgate Series in which competitors accumulate points from 39 tournaments around the world include Austin, No. 1 in the world currently on the Women's Tennis Association computer; Hana Mandlikova, Chris Evert Lloyd, Martina Navratilova, WENDY TURNBULL, VIRGINIA RUZICI and the new baby of the bunch, ANDREA JAEGER, 15. The eighth spot in the championships, double elimination until the knockout semifinals, has yet to be clinched but RAY BENTON, tournament director, is "95 percent" sure PAM SHRIVER, the Austin contemporary from Baltimore County eighth now, will nail it down. . .