Option 1..leave SYD at 9 am and arrive to BKK at 435. Leave BKK at 835 pm and Arrive DOH at 1130 pm the same day. The first flight is 9 hours second flight is 8 hours.
Option 2...leave SYD at 730 and arrive to HKG at 330 pm. Leave HKG at 630 and arrive DOH at ten pm the same day. Both flights roughly the same time.