You can begin to contribute to a building society while abroad, we contribute to NHT only because while my husband was working in a hotel, they contribute a percentage to the trust automatically. You can also link it to Scotia or a Jamaica National mortage. Im not sure if you can apply for NIS # while abroad, but we applied for my husbands TRN from Canada ( I already had one because our car in Jamaica is owned by me). Having a TRN has only become mandetory in last 4 years. It took 1 day to get the temporary number.
Hope all works out in JA for you