I have no clue. I don't even know when it will be coming to the USA. I wish she was done with it, but I don't think it will be done till next year. Did anyone know that J.K. is having a 3rd baby?
Best bets so far are Spring or Summer 2005 - June / July probably.
No one, not even her publisher, suppliers, or bookshops know a more exact date.
She says on her website that having another baby (congratulations, btw!) will not affect the progress of the book (called 'Harry Potter and the Half Blood Prince')