I started applying as soon as I had completed my MCC and got called for an interview while my paperwork was down at Gatwick getting processed. Had to make a special trip down to CAA headquarters to pick up my blue book the night before my interview. Bit stressful as it was my first interview and didn't want the bad impression of turning up without my licence, but the people at the CAA were very understanding and fast tracked my application a bit to ensure it was ready in time.
I would find out when the latest you should get your licence issued is and start applying around then. Its only a couple more weeks to wait, which isn't that long in the grand scheme of things.
PW