Another clue to the code

I had to update yesterday's clue ... I mentioned that 3 of the 5 numbers would not change.  Actually, they will all increase - the 2 remaining numbers will increase one final time.

The code written on our gifts:
0, 8, 18 or 19, 20, 22

Remember - it doesn't put everyone in order by age. 
Clue for today ... If I was assigned a number, I would be 23 (abnormally low for an adult).  John would be 26 (abnormally high for an adult).  In fact most adults/older teens would all have the number 24.