Owen, the only time I think you will waste money on adwords is between 9pm & 7am ( who looks for a carpet cleaner in the middle of the night?) most normal people will look at normal times.
I would run your advert 7 days a week, I've never seen any data that says .. eg:Tuesday and Wednesday are better than sat & sun.
If anything I would do it weekend with the words aimed at home owners and during the week at business customers ( who only work weekdays)
There's a lot more to adwords as you start experimenting