You can check your latency by opening the Resource Monitor, going to the Network tab, and then checking the "ffxiv.exe" image. The latency will be listed in the TCP connections section.

If you are with Telstra Bigpond or Optus then you will likely need to use a tunneling service such as WTFFast. This is because Telstra routes Square Enix traffic through Singapore/China, and Optus routes Square Enix traffic through America. iiNet, Internode, TPG, etc, route Square Enix traffic directly to Japan.

You will ideally be getting 100-180ms on an optimal connection depending on your location.