I haven’t travelled to NA with CX post-pandemic so these are general answers:

Both HKG and NA:
- bear in mind lounge access is day of travel and up to 6:00am the next day (see use of 6am rule iro a MH outport SIN DO 2023: 13 - 15 January 2023: USA Martin Luther King Jr Day Weekend )

HKG:
- any CX flight on same day

NA:
- easiest if you can obtain mobile BP (should be generally OK if you’re flying to HKG these few months) and have HBO
- if you have check in bags then checking in in earlier flight’s desk is possible but not by right Earliest check in time for CX138 SYD-HKG (also see https://www.flyertalk.com/forum/brit...l#post35101634 )