For all "how long does it take from A to B" questions, I love the Transportation Wizard link on OurLaughingPlace.com you enter start and end locations and it tells you how to get there (car, bud, monorail) and how long. Add on up to 20 min wait for a bus and your walking time to and from the bus depots and you've got it!
In your specific example, they say 23 min by disney bus.