Okay. It's been my experience that an actual conversation between two people is more effective than a 2"x2" piece of paper, especially when getting the employee name. Clearly your mileage varies.
Look at BWV all you want. DVC check in time starts at 4 PM, and checkout is up to and including 11 AM exactly.
You shouldn't get a room prior to 4 PM. DVC units are two to four or more times larger than resort rooms. They have, at minimum, kitchenette if not full kitchens, including appliances. Many have multiple bathrooms. Most have washers and dryers. It takes longer to clean a DVC unit than a resort room.
It's not that they want you out early. They want to be able to start cleaning the units as early as possible, and if the departing guest doesn't provide any update on actual room-clear time, well, the housekeepers aren't psychic. They have to find out somehow, and knocking seems efficient.
Members dissatisfied with the previously advised check in and check out times should probably express that displeasure directly to Member Services.