I actually had very good luck with making ADR's exactly 90 days out. I was able to use the 90+10, but I could not get certain ADR's that I wanted, or I got times that were not what we wanted, or we were at two separate tables. I checked back on the 90th day, and was able to do much better. I truly believe they hold some ADR's back for the 90th day.
For example, I called on 6/27, which was our 90 day mark since our trip starts 9/25. We wanted to do CRT on 9/26, but it was all booked up for both breakfast and lunch, so we booked it later in the week. The next day (90 days from 9/26), I got online at 6:00 eastern time and checked for CRT for 10:00 am - I was offered both 9:45 and 10:15.
Another example, we wanted Tusker house for breakfast around 10:00 am on 9/27. The only thing they had available when I tried to use our 90+10 option was 9:25, and we were at separate tables. I then checked back exactly 90 days before 9/27, asked for 10:00 am, and was offered 9:55.
It may not work out perfectly for you, but there is a chance you will get what you want. I had some issues booking with the 90+10, but checking back exactly 90 days out I got what I wanted, within just a few minutes of the time I wanted.
I would definitely try to do them online though, as that will give you an hour jump on those that are waiting for the phone.
