Got an offer that includes option for Maui:
$1,099/stay (+$191 tax) (4 nights) at Astin Ka'anapali Shores or Royal Lahaina. +50,000 HH points.

I think we have stayed at the Royal Lahaina before with parents (they have a non-Hilton timeshare) and it was decent. We would like to visit Maui on our next trip.

My question is (I can't find anything on the terms & cond.) how do I find out about availability and possible black-out dates?

edit: (If I go ahead with the purchase process online, I can select my dates, but it says that they are not confirmed until two dates after I purchase - I don't want to buy this and be stuck traveling at some time I dont prefer.)