I believe the ride from EPCOT to TTC is between 7 and 8 minutes each way. So, add in loading wait time at TTC for the return, and you're probably looking at just about 20 minutes for a round trip.
Ehhh.... depending on the driver, how many trains are running, and the position of the moon in relation to the sun... eh... 26 minutes. Give or take. Your mileage may vary.