My two cents
I recently when through the CTC system at 26/27. Almost half the guys on my course were 19, so it seems to be more the norm. As long as you've got some life experiences to draw on for interview questions then I wouldn't worry about age.
In terms of getting an airline job, CTC seems to have a huge advantage albeit for a price. But that's another debate, I'm sure you can find plenty of people for and against by using the search function.
Good luck!