If you have a 4G phone (specifically one that can operate on 2300MHz), take a walk to the point that you would like to have your NBN set up, go in to Settings-Mobile Networks->Network Operators->Search Networks. If you can see a network called 50213 (or similar, I'm in the city at the momnet so I'm doing it off the top of my head)), then you should be able to get teh NBN at that specific location and would be worth booking a technician to do an install.
If you can't see a network with a similar name, then there is no NBN signal at that location.