depends if you go on I-4 - maybe 15 minutes - just don't go on I-4 between 6:30 -9am and 4:00 to 6:30pm
International Boulevard - probably add 5 minutes more.
the first exit on I-4 after Seaworld (you are going toward Tampa) is Downtown Disney - then Epcot - then MK -
On International Boulevard - stay on it until it ends - left lane goes toward the airport - the right lane will become World Drive after you pass the big Marriottt World Center. - after DD, then Epcot, then MK.