From what I've heard so far, Team Avatar will be somewhere in their 20s in the movie, so I think about 10 years after the finale. I'm not 100% certain though.

There’s an official post somewhere. You can look it up.

No matter Aang is 100 plus whatever the number is

So Aang will be 124 chronologically and 24 biologically

Well After the war that's for sure