I'm trying not to read any of the spoilers but I guess my question goes in here....
When do I unlock the middle and left islands?? I'm up to the point where the Romans flat and taxi business have been set on fire and I've moved to a new flat on one of the smaller island (about 19% completed). The main bridges still have a police barricade on them .
Not long to go until you get to the second island. Maybe just over 5 more missions?
You still have a while before you get to the third island.