One of my friends from camp is currently a Cadet Sergeant with the Royal Canadian Air Cadets, and he is 17 1/2.
He joined when he was 14, and in his case, should have done his Lvl 1 and 2 training in the same year, then 3, 4 and would be in Lvl 5 this year.
However, he did Lvl 1 and 2 in 2...