Don't know if it's possible for you to change, but when I went to ZAN I took Zanair who had a guranteed connection with the inbound BA flight. When we arrived in the terminal there was a Zanair guy with a sign with our name. He took us to the head of immigration queue, then collected our bags and walked us to the 'Pirvate' terminal. I'd say we landed in ZAN within 60mins of landing in DAR. Enjoy Zanzibar. It's going to be the new Maldives!