When travelling in F you can have whatever combination of food you like at whatever time. CX does, bizarrely, default to breakfast just before evening arrivals on some of its flights, but in F you just tell them you don't want to do that and they will provide whatever you want, subject only to them having sufficient stock on board. Feel free to mix and match. Personally if I was taking that flight I would try to sleep as little as possible the night before, sleep immediately after takeoff, ask the crew to wake me in, say, 5 hours, and serve breakfast (at about 10am HK time, with eggs cooked to order), then to serve late lunch / early dinner before arrival into HK at, say 5pm HK time. There are, of course, snacks (or anything else from the menu) available in between if you get peckish.

As with the first time for other things in life, the bast advice is to relax, not get yourself over-hyped (so that it would be almost impossible to meet your expectations), and don't try too hard to enjoy it.