Did Omega Ring update drop at 11pm (GMT) or is it delayed?

Instead of leaving the Xbox Insider program as one Ambassador has suggested you can drop down to a lower ring which receives much fewer updates. For example if you are in Beta ring drop down to Delta or Omega. The Omega ring receives the fewest updates,
usually just before it is released to the general public. This can be managed using the Xbox Insider Hub on your console.

Any idea on the time it'll come out in Aus? 11pm gmt+10(Qld)?

Hi, as they say you can't have your cake and eat it, those insider updates are mandatory and will be pushed to your Xbox despite you having automatic updates disabled. Your only option would be to remove your Xbox from the insider program totally or drop
down to the Omega ring where updates may be less frequent. I'm in the Alpha leap ahead ring myself and those regular updates are just a part of being in the program which I expect and accept.

The new update is only out for some Alpha & Alpha skip ahead insiders at the moment.

If you're in the Omega ring then you'll probably be the last ring to get the update before it's released to everyone.

In my understanding the Dashboard experiment, A, B, C selection, is totally random.

As "Both consoles say their OS Version is (19h1_release_xbox_dev_1911.191028-1335)" your consoles are either in the Beta or Delta ring.

Both those rings and Omega ring are getting a preview update News release notes Beta Delta Omega
Insiders today, which you can manually start or wait until it becomes mandatory.

After you do the update, if you want to change rings, it will be the perfect time to change as all those rings will be on the same release. Subject to eligibility.