My window opened on Sunday, 2/3. There was nothing available for CG Brunch when I looked at 7 am EST that morning. Yesterday evening (2/5), I was able to get a reservation for 8/4, and when I booked I had my choice of times. It looks like CG Brunch reservations for 8/4 did not load into the system until yesterday evening, which was 180 days from the date of my reservation. So, if anyone doesn't get the reservation when your ADR window opens, keep looking. Especially close to the 180 day mark from the date of the brunch reservation you want.