NSW的官方答复来了,注意红色的部分。理解不错的话,应该是从长登日算起。
Permanent residents of Australia under the Commonwealth Migration Act 1958, are allowed to drive or ride in NSW on their current overseas licence for a maximum of three months from the *date they arrive in Australia. Permanent Australian residents need to obtain, not just apply for, a NSW licence within this 3 month period if they wish to continue to drive or ride in NSW.
* This is the date you arrive to reside in Australia – eg: not as a visitor