Unfortunately I haven't done CX897 that I can remember before, but am at TBIT 6-7x annually departing on CX, here are a few general thoughts:
1.) I haven't done CX897 in F. But I was just on CX830 a few weeks ago, which had a 9:15am departure time (vs. 9:30am for CX897), and the "first" meal was lunch. So I think your "first" meal will be lunch too.
2.) Just a reminder, dining is on-demand. If you're not too familiar with CX F they will ask you what you want soon after takeoff. The menu is presented in a fashion that makes it appear in sequence. Further, the FAs often will assume you want something soon after takeoff and often don't spell it out for you that's it on-demand. However, you can set both the timing and menu items to your liking. So you could first order something from the "second" meal on the menu, then have a snack item second, caviar a few hours later, etc. The order of the menu is irrelevant although it looks deceptive.
My point in saying this is
regardless of what the "first" meal is, you could easily have breakfast in the lounge and then board, and make yourself a lunch 3-4 hours later, by selecting one of the second mains, an appetizer, one of the snacks, etc.
3.) TBIT departures have improved since the renovation, with the exception of security...which generally still sucks. There aren't many early am departures ex-TBIT so my suspicion is things will be okay. I've departed from the new TBIT perhaps 10 times now, usually late night, and the J/F line can vary from 10 minutes to 25 minutes. Sometimes it is patrolled well - for example, I was there earlier this week and I was funneled right into the front of a security line. Result: 10 minute traverse through TSA, tops. Other times the security line seems to merge with the regular line and you can be up for a 20+ minute, aggravating wait..because you're so close, and moving at a snail's pace. Pretty terminal, same crap software.
However, overall the vibe is a lot nicer now if you're into that thing. Shopping has improved dramatically, there are wide open spaces with high ceilings, feels very "bright", it's actually pleasant to walk through now....versus the prison-esque feel before. If you haven't been to the new version before maybe it's worth an extra 20-30 minutes early.
Lastly, you're almost certain to depart from a "regular" gate. Uncertain on the #, I've been both in the 150s (left hand side) and 130s (right hand side) on CX. At night, they have an unfortunate habit of sometimes leaving one of the birds at a remote stand, which means getting bussed to the gate...which blows me away given TBIT is brand new. But I don't think that happens with CX897.
4.) The QF lounge is nice enough, and if your only option is eating there or not eating at all before the plane, by all means do it. The food in F is good on CX.....but QF F food will be better, it's prepared on the ground after all
. However, I think the QF F lounge has been grossly overplayed by the travel bloggers. I've been in there at least 5 times now. Perhaps I'll get flamed for saying this, but I really wouldn't go out of my way for it. I'm not opposed to enjoy lounges in general if time allows....indeed, I do that at HKG these days with Pier F, with I think is a very thoughtfully designed space, with a lot of unique areas, quiet spaces, power outlets, snacks / drinks intelligently spaced around the place. For me, the QF F lounge is utterly uninspiring relative to the hype, the space is basically a massive rectangle. It gets surprisingly crowded in the evenings. For many simple things, you have to go over to the bar and get service...two nights ago, I ended up just asking for a 750ml liter bottle of water from the bar, because otherwise you have these small cups and have to keep going back for refills. My preference, I just don't think it's as thoughtfully done as some of the nicer spaces globally and isn't as cool as described in the fawning blog posts I've read. The food is decent as you'd expect at a good F airport lounge...ie, still not a real restaurant, despite whatever celebrity chef that has stamped his name to it for some royalties. I think the fact they have table service at a US-based lounge has gotten everyone over the top.
If this matters, let's say I have an extra hour or two with nothing to do in Hong Kong pre-flight. Since Pier F opened, I have found myself going to HKG and using Pier F. Ex-LAX, with the shiny new QF F, my departure habits haven't changed at all since the QF F lounge was created....I still find myself trying to get there at the absolute last minute, get my BP, clear security, and walk to the gate. That lounge just doesn't do anything for me. Could just be personal preference.