I weigh myself once a week, I resist the temptaion to do it more than that because, like the others have already said, your weight fluctuates for various reasons (even with in a 12hr period)... which can make daily weigh-ins a disheartening expirence.
That being said, I weighed myself at the last day of my first week and I did see a loss.
And also it helps to take your measurements (if you havent already) becasue many people find that they seem to lose inches before pounds... and any loss is a good loss