It is kind of silly to stay up all night, then get on a plane dead tired so you can sleep on an airplane seat bed. I imagine that you will be more jetlagged than if you had gotten a good night of sleep, and slept periodically on the flight over to HK.

People take these flights every day, most in coach and J, I suspect you will be fine, if you get good sleep the night before, nap on the plane, eat light, refrain from the krug and other beverages and stick to water and tea.

I am taking CX841 to the connecting BKK flight on June 14 in F. I have done this flight before in F and had no problem with jet-lag. I actually slept the middle part of the JFK-HKG flight for about 6 hours, starting about 4 hours after we left New York. I slept about an hour on the HKG-BKK flight. Arrived around 5.30 pm in BKK, was at hotel and in room by 7 pm. Showered, went to club lounge, had a snack and went out around 8.30 to a few BKK bars. Back in hotel at 12:30 am. Went right to bed and woke up at 8 am without any issues.

To me the key is sleeping just enough on the plane to allow me to stay up to normal bedtime in the jurisdiction. I am always surprised by people flying from LHR to JFK on the evening departures on AA 4:35, 6:30 or 8:05 pm, they sleep the entire flight, so when they get to NY it is around 8, 10 or 11 pm. I imagine thatit is then hard for them to go right to bed or get a true good night sleep.