[polymatter]

For many people the standard communication medium nowadays is not a voice call but an asynchronous chat message. I wouldn't bother looking up the time in Melbourne, I'd just send a WhatsApp message. Uncle Steve can reply at his convenience.

Bare in mind that just because Uncle Steve is awake that it is not necessarily convenient for him. In the scenario he likes to stay in bed a bit later. This is no problem if you simply send him a message. No need for any lookups or actuarial tables or astronomical calculations whatsoever. If we want to voice chat we can do so after he has responded to the asynchronous chat message.

Bare in mind that the answer to "what time in it" post timezones would be "mid-morning", or "late evening" or "noon". ie. conveying the information you actually need.