Spoke to reservations people at HOB. They told me that they don't take reservations before two weeks prior to reservation date.
However, there is a reservations link, on the HOB, Orlando web site.
I would suggest making a reservation on the web site first, they send you a confirmation number.
If that doesn't work call, but do have a reservation, prior to arrival.
They tend not to have any open walk in tables, during the busier times of year.