Ah yes, I forgot to address that. It is true the graduation date is 17. If you don't meet that criteria than you will simply graduate later compared to others. So Cam will graduate after another 4 years where as Omar maybe held back 3 years. Another option is you can show one of your characters hasn't arrived to Innocence yet if the age gap is too much, though that would leave you with only one character to control.

While I say class, again its not per say a school. There is no succession, there is no softmore, highschool, O levels, A levels etc. Its simply a harsh training environment with various lessons and continuous drills to make you the best soldier you can be.