Go to Edmunds.com's maintenance guide website and enter your make model and year. Then enter your mileage and zipcode. You can then see the recommended services including transmission fluid changes. Sometimes, there is no scheduled change for the transmission ATF, only the check and top off procedure. In that case I would say you should flush and change the ATF fluid and filter every 60,000 miles as a preventative measure.
The website link is http://www.edmunds.com/maintenance/Main