I live in public housing and only have a 60 litre HWS but that is a very expensive small heater as it has instant or rapid recovery heating meaning that as water goes out it comes back in and heats.
I turn my HWS off all day until 40 minutes before I have my shower at night. If you have a 125ltr or larger tank you would possibly be better off not to turn it off as the larger tanks store water and keep it at the desired temp. You can also lower the temperature it heats to as well.
Always use cold water for washing clothes unless they are greasy oily.
Only dry clothes in a dryer on warm.
If yr HWS is in a cupboard hang stuff in there. HWS do throw out a lot of heat in a cupboard, why waste it.