It started July 18. Onsite guests can make their ADRs all at one time (up to 10 days worth) 90 days from the FIRST day of their trip (check in day).
Offsite guests can still make their ADRs at 90 days but one day at a time.
It's a new onsite benefit. I've heard though that they still hold some tables at restaurants like CRT for offsite guests at their 90 day mark.
Hope this helps.