Hong Kong is 1.5 hours behind Adelaide
Best overlap: 9:30 AM to 6:30 PM in Adelaide is 8:00 AM to 5:00 PM in Hong Kong.
Aim for 9:30 AM to 6:30 PM Adelaide time — that's 8:00 AM to 5:00 PM over in Hong Kong. With 9 hours of daily overlap, these two cities are an easy pairing; almost any reasonable hour works. These times hold for most of the year, but Adelaide's daylight saving (which Hong Kong doesn't use) shifts them by an hour twice annually.