Yes and no.
Our company registration portal is accessible 24/7. Registrations are processed around the clock, so, provided the application does not need to be manually reviewed you will have your ACN within 2-3 mins.
If your application is flagged for manual review by ASIC then it will not be finalised until regular business hours recommence.
Similarly our phones, email and live chat features are manned 9am-5:30pm Mon-Fri.