Hi,
The fastest way to get there is to take a taxi, but if you want to use Disney transportation I would allow at least an hour. It may take you less, but you need to get from your room to the bus stop, possibly wait a while for the bus, ride the bus, get off the bus, walk over to the boat dock, possibly wait for the boat, ride the boat, then walk from the boat dock to the BC and into Cape May.
Also, if you are interested in walking from the Studios: unless the boat is loading up and ready to leave when you arrive at the DHS boat dock, it will probably be faster to walk over to the BC.