We just completed our vacation and did a split stay between BWV, BLT, and VWL.
We did have a rental car for a few days (the days of the switch) which made it easier to go from one to the next. When I was going from BWV to BLT, I thought I would try bell services and brought down my luggage for them to transfer. Left it with them and headed off to BLT to check in around 7:30 am. We didn't think our room would be ready, but it was. But we headed off to MK for the morning.
When we moved from BLT to VWL, we took our luggage (since there had been a problem with the BWV to BLT transfer) and checked in around 8:00 am. Left luggage with bell services since room was not ready and just headed out to AK and DTD. They sent us a text around 1:30 pm that the room was done.
The only piece I can say--if you use bell services to transfer your luggage, it won't arrive to the new resort until sometime in the late afternoon (3:00 ish). If you think there is a chance you will head back to the resort to swim while you wait for your room to be ready, be sure to keep a separate bag with swim stuff that you don't have them transfer (take it with you when you check in to the new resort and leave it with bell services there--at least if you come back early, you will have access to it).