Be an independent thinker, set it like you want it. If it seems a little fast, slow 'er down, if a little slow, speed 'er up. Once you get it like you want it, don't tinker with it. Bill W.
I usually set the idle by the sound. I like to get the pukka-tikka-pukka-tikka sound at idle. What speed it is, I don't know, but it has that classic A sound.