I agree with the PP, it will be close! Make sure to view the parade near the train station and head out ASAP.
However, you don't have to take a boat to WL, there is now a direct bus from MK to WL!! It doesn't stop anywhere else, so you are looking at about a 5 minute trip from pick-up to drop-off. Not nearly as much fun as the boat, but certainly much faster. Also, the bus stop at the WL is closer to the main building then the boat dock so it will be a quicker walk to the lobby once you reach the lodge.
Have a great time!