There are no buses between DHS and any of the Epcot resorts...not going to be an option to BC.
When leaving DHS, with the canal on your left, buses to your right, walk past the canal, staying on the sidewalk. You will notice a pathway/sidewalk going down towards the canal. There should be a sign there that tells you that is the way to BW. Stay on that walkway...take you right to the BW. You can then go left and up and over the bridge, go right on the bridge and it takes you to the YC/BC.
The boat will take about 18 mins from DHS, but that doesn't include any wait times for the boat to get there and load. But once it leaves, it takes under 20 mins.
For a 5:30 ADR, at BC, you should leave DHS by 4:45....better to be early than worry about your time.