The eldest cadet was turning 30 when he was in ADL, he is now 34, S/O on A340.
I have seen S/O with age 38, so it is not too late to join at 30, but perhaps it is too late to start a new career if you already have one.
MNG: Don't have to worry about pay too much, it will have enough money for food. No matter how you look at it, if you successful, you will receive the least money anyway (local scheme!)