Sprint times

As I've been looking over the various Sprints available in CO this year, I've noticed that there is no 'standard' sprint distance tri. Some have 750m swims, others 500; rides seem to be between 10-15 miles, and the runs are anywhere from 2 to 5 miles. This is ok; I'm 'goaling' for a 500m/15M/4.5M. There is one a week after that's a 400m/10M/3.1M that I might do as well.

The past two years, I could always track my run times, and compete against myself. Being that a tri will be new to me, and knowing that I'm slightly faster than a sloth at running, what should I consider a respectable time? I'm very self-competitive, and having an idea of a decent first time will help motivate me. I guess I should add that I'm 38, and I'd be in that Clydesdale category.

Thanks!