Happy Hatter Parties were very accommodating when I had to change the date of my son's party at the last minute. They had to find another entertainer at very short notice and she managed to keep all of the children very well entertained for the hour and a half she was there. The only thing I'd question would be the theme - we asked for a Jungle theme which wasn't as obvious as I would have liked but considering everything was rearranged at the last minute, my main priority was my son enjoying his party - which he did!