It is 100% dependent on which entrance the bus driver decides to use and what time of day. If they use the Main Entrance the order is:
Martinique
OPR
Trinidad North
Trinidad South
Jamaica
Aruba
Barbados
If the driver uses the back entrance the order is:
Jamaica
Aruba
Barbados
Martinique
OPR
Trinidad North
Trinidad South
Now during the morning rush they send 2 buses for each park. One bus will pick up in this order:
Jamaica
Aruba
Barbados
The other bus will pick up in this order:
Martinique
OPR
Trinidad North
Trinidad South