Your HWS is on a CL (controlled load) circuit ??
Check with your DNSP (or through AGL helpline), as some DNSPs have different CL tariffs available, with more than one cycle per day.
Here in SA CL is now set to come on during solar soak, when the state generally has more renewables available.
I know I have seen NSW users mention they have at least 2 (maybe more) tariff options, and CL options.
If you have a CL meter, you can see the specific times of use in your data, available to download form the AGL accounts page, go to usage and click the little download data icon.