My first flight ever was a very short STR-FRA hop in 2000.
Fanta was my favorite drink till then but they only had Sprite loaded (so my favorite drink changed then and there)
After a few flights within the EU my first proper long-haul, which is the more relevant memory I'd say, was QF6 (FRA-SIN) back in 2005.
I had just truned 10 and we were heading to SYD for a vacation to celebrate me finishing elementary school.