At a minimum install the brackets during the fuselage build. Someone mentioned the brackets now come with the fuselage kit. If you did not receive them, order them. If you can afford the autopilot kit now, do it all!!

It was not yet available when I assembled the fuselage.
 
autopilot brackets

I wasnt supplied the auto pilot brackets in my kit can someone tell me the part numbers for the brackets
thanks
 
According to my fuselage packing list the brackets are item number '12 AP Brackets' description 'Autopilot Bracket Kit' so I guess that's what you'd order?
 
Auto Pilot Installation

You can install the AP brackets and the servos after the fuselage is done, as long as the fuel tank isn't in the way....its darn awkward, but do-able if you can still wiggle and twist yourself into the baggage area...I did it but would MUCH prefer to do it while constructing the fuselage...the servo itself for the roll would not be a great challenge but the brackets were the real pain installing them after the fuselage was finished. If I had to do it again I would work out of sequence until I had the brackets and the servos in hand.
 
would it better to install the servo's when building the fuselage or after.

Like anything else, during the build would be much easier. After works but you have to take things apart...panel, floor etc. We only did it that way because they didn't have it then.