Just as a future FYI.
Park reservations opened automatically for me today.
Apparently it is based on the window of use for the ticket.
Ticket is good for a certain time frame from the purchase date. It opened today since my ticket was goo for any 10 days from August 1ST.
BUT, it will only allow me to book that first day. So I will either have to wait till Friday to book all days , or book a day at a time as they window progresses.