We were there in late November. The first stop is currently Martinique, Aruba the last, so Jamaica is second to last.
Sometimes they split the resort up into A- and B-side. A-Side is Martinique, OPR, Barbados and Trinidad. B-side is Jamaica and Aruba. I can’t remember what the driver said when they do it, but usually in the mornings the bus left the resort after Trinidad.
In the afternoons even being at Martinique does not guarantee a seat or that you can enter the bus. One afternoon we had to wait for the next bus, as the first one was full with returning guests. But that was the only issue we had.