If you are relying on WDW transportation (i.e. busses), 75 minutes.
the ride itself is about 20 minutes. But the wait at DTD can be a long one (45+ minutes). You may be lucky and catch the bus earlier (especially if there are many guests waiting at the CR bus stop).
IMO, the dispatcher will route the busses to the stops with more people waiting. So, if you are the only guests waiting for the CR bus, you will wait quite a while.