Hello - I live in Prague. I agree that if it's scheduled to start on the 1st, it will do. They changed the style of the Christmas market last year - better-looking huts, and more of an emphasis on selling proper Christmassy things (too many stalls had been selling general tourist things), more food.
Give me a shout and we can meet up on the Old Town Square I live about five minutes away. Although we're going to Australia for Christmas, which involves going early in December/poss. late November to get cheap tickets (as yet unbought due to slight post-baby shortage of money...)