You'll need to check in at Guest Relations, which is near the front of the park ( to the left of Spaceship Earth as you enter Epcot.) So if you walk from BCV to Epcot, you'll enter at International Gateway and walk through Epcot to the front of the park. That's a pretty long hike - I'd drive if you have a car or take a taxi to the front of the park, or wait for an Epcot bus, but I'd be at the bus stop by about 7:45am just in case a bus was late coming.