When you finish line training you get full FO pay backdated. Ie you do get paid during the line training period, but you only get ur hands on the cash for it if you sucessfully complete the training.
They are basically trying to ensure that they don't pay any money to someone who doesnt make the grade. Somewhat of a pain to have to use my credit card to live off for a month, but not too bad to put up with in comparison to some other airlines out there.
Hence the reason why I am keen to get the line training done as quickly as possible. I want my money!