Varies...I have had no waits but also had waits of 20 mins. Once you get to the bus lines, your time will depend on when the last bus came and went. That wait could be up to 20 mins. Then, once the bus comes, again, it depends on how long the bus has been sitting there. They can sit and wait up to 20 or so mins.
So....let's say you get to the bus lines, at the end of a longish line (maybe 25-35 people). You wait about 5 mins, the bus comes, and everyone boards the bus. Your bus will also, most likely, transport those going to CSR and POP, so they will board as well. Now, with that many people, the bus may be pretty full, so it will leave after about 5 mins.
But, if you get to the bus line, just as the bus is leaving, you could wait up to 20 mins. Then, once the bus comes, you will be among the first to board it, so may face a longer wait, on the bus.
Best possible scenario??? You get to the bus line, with no one in it, the CM waves you on to the waiting bus, you get on, the bus doors close and off you go. That has happened to me about 3 times.
Plan on it taking you, on average, 70 mins from the time you leave your gate area to the time you reach your resort.