Do you mean fron Universal Studios to MK? I didn't understand your question at first. I'm all about Disney and it didn't register about US at first. If that is what you meant, I'd say give it an hour to get between the two. If I'm still wrong about your question, sorry! Sometimes I even confuse myself.
At 6pm on a Thursday in December, you'll need about an hour to get from Universal to MK, including the time it will take you to get out of the US parking lot and into the MK parking lot. Add at least a half-hour for getting from your car to the actual front gates at MK.