It's so individual that you just have to try it. As posted by topflight pro, I usually prefer to stick to one cog in back and make all the changes up front. At the cat 3 level, the baseline should centered on the historically accepted 90", about a 50x15.
Points race 50x15
Scratch 51x15
Keirin 52x15
Elimination 49x15 (I don't know what Minnesota is thinking by going UP in gearing for an elimination)
Madison 50 or 49x15
Tempo 50x15 if ridden properly, 51x15 if ridden slowly.
Masters riders often feel more comfortable at lower rpm, so you might end up bigger, but I'd start with the above recommendations if I were you.
You can also figure out the 14t equivalents if you use a 14t. As you gain experience, you can then modify this a little depending on your strengths, the pattern of competition, and the speed of the track.
If you're doing multiple races in an evening, some riders end up gearing one tooth down for later races.