I have put my kids to bed earlier or later depending on time zones. I also advise taking a walk outside and getting fresh air your first day there. If you need to nap, try to do that, but stay close to the destination’s schedule.
I’ve been on many long flights with my son domestic and international, from the time he was 6 weeks old until present day (he’s 4).
I try to think of things that are cheap, easy to pack and replaceable.