If you can paint the house before the skirting/doors/ etc... are all in, all the better, this means you can go hell for leather on the house and I personally, after painting my house would advise, get a painter in to spray paint your entire house in undercoat first, you paint the rest of your house yourself. Should only take him 4 days to do or you can do it yourself... I did the undercoat in my house and I honestly thought I would go mad, it was very tough work as you really only get one roll and you have to go back to get more paint and hence forth a million and one more times. I would save your energy, for the nice bit, the colours! But try and get it done before the wood goes in, as then you can paint away without having to go steadily around architrave, skirting etc., takes up a lot of your time aswell as splashing the wood, which the paint will do.