1)Do it when you are likely to be most fit..make your own mind up on that one, but once you settle into a normal routine at your posting it will revolve mostly around getting on the p*ss and eating crap, so the clues are there.
2)stop stop stop saying "like" at pointless times, you sound like fcuking Shaggy - like.
I reckon after Chatham would be a good time to do it. That is depending on how you spend your time there. I spent most my time there on the lash, however a lad on my course spent most of his time attending training sessions ran by a qmsi, which was also attended by 59 sqn lads who were on course at 1 regt also. They gave a lot of good advice aswell on prepping kit and all that stuff, some of them had come fresh from the course having done it straight after phase 2. My mate went on to pass the AACC on his first attempt. Hope this helps.