The buses don't arrive at any particular place at a set time... like "we'll stop at CBR Martinique at 8:06 am".
Basically, you go to the bus stop and hop on the bus for your destination... Magic Kingdom, Epcot, etc. There are very few buses that go more than one place (water parks are usually on same bus as another location or some resorts are combined on one bus).
Basically, buses travel...
from resort to specific park and back
from resort to DTD and back
from one park to another park (this doesn't apply to all parks)
Buses to NOT go from one resort to another (unless they share a bus on the route). Buses do NOT go from the parks to DTD.