We always allow 20 minutes just to wait for a boat. So, for MK to HDDR, I would be at the boat dock about 40 minutes prior to when you want to arrive at Ft. W. Pioneer Hall is a quick walk from the boat dock. If you are early, you can tour the stables, go to the playground and/or the gift shop.
Same with DHS to B&C. It's about a 15 minute boat ride, so I would be at the boat dock 40 - 45 minutes prior to when you want to arrive at B&C. Again, you might be early depending on when the boat arrives. You can walk, but it's kind of a trek to BC. If walking, I would allow at least 30 minutes depending on how fast you walk.