our flight departs 425pm and we get in to hong kong the day before at 240pm on a J cx redemption
I wouldn't worry too much about lounge hopping. The best CX F lounge is the one opposite Gates 1-4. Immediately to the left after you have comlpeted immigration.
What is this lounge called ? I've heard CX have many lounges in HKG including the Cabin, the Pier, the Wing, the Haven, etc
If you don't enjoy F the noodles are better in J just jump the rope at the end of the lounge !!