In 1999 I went through BA's selection with the promise of a start date within 4 months or so.
Well it would have been so if it wasn't for the recruitment being halted for another year to 14 months.
The good news though is that BA really keeps you on file and even call you once in a while to make sure you are still interested. In fact, during this waiting period they actually offered me a contract with EOG (Euro Gatwick) on two occasions. (Turned it down twice because I was only willing to join on a mainline contract). So when pretty much a year and half later after the interview, the company offered me a EuroFleet position, I decided to go for it.
All I am saying is that when dealing with airline jobs, it is a good idea to keep your options opened at all times. I have been in the holding pool for two different companies and both times it has been for over a year and half.
No regret of course because in both cases it was worth the wait...