I'd definitely leave it until you have driven it for a few days or a long few drives etc. My idle will be all over the place after the battery has been reconnected while it re learns it.
Not sure if they will always be the same or same for each car but usually mine will idle really high on start up (2k - 3k) and then settle a bit later (but not to the usual 0.8-0.9k). Another way to tell with mine is if I get to about 50mph or so and then knock it out of gear to coast. In normal running the revs will drop to normal idle but when things are resetting the needle will drop but it will bounce from 0.5k to 2 or 3k constantly on the way down on coasting and slowing down. Not sure if that is standard across the board with all Altezzas though or just a trait of mine or the road conditions etc.
My advice is leave it for a while and see if it settles before playng with anything!