Which is Exit#6, State Road 536, to enter Disney. It becomes EPCOT Center Drive on-property. The first exit once you pass under the Disney Welcome barrier is the exit for DTD and is well-marked.
If you somehow miss that exit then the next one is Exit#3 which is Osceola Parkway. That heads into Disney World as well however there is a $.50 toll on the exit ramp off the 417 and this one is coins only, no staffing.
BobK/Orlando