Depends on a lot of factors. Time of day, if you have a car or not, etc.
If you are going by car outside of peak time to get to the MK, allow 10-15 minutes.
If by WDW bus, and the MK is open, 13 minutes by bus, and another 5-10 to walk to the CR. Also whatever time you need to wait for the bus to arrive--can be up to 20 minutes or more, usually 5-15.
If the MK isn't open, and you have to transfer via DTD, it can take up to 90 minutes.
Hope this helps.
Anne