Just been checking news items in the Opera browser. It's Sept 28th & articles released one hour ago by Macworld Australia are letting us know that iOS 11 will be released on Sept 19th & macOS 10·13 on the 25th.
Duh!
In further news, though, Australia will be the first country to get the 3G version of the rehashed Nokia 3310 (with Snake game) and it will retail for $89.