Once you board it is roughly 5 minutes to the Epcot entrance (note I've never timed it, that's just a best guess). And then a 5-10 minute walk from TTC to wherever in Poly.
On edit, Googlemaps says that it takes 10 minutes from Epcot to TTC on the monorail. That seems a bit long to me but who am I to argue with Googlemaps.