I believe the online system "turns over" at 6am. You will be able to book 180 days from the first day of your reservation and will be allowed to book for the next 10 days of your trip on that day as well. The phone system opens up at 7am.
I think that's right. Make sure you have you resort reservation confirmation number. I seem to always have a problem using Explorer and Chrome but have had good luck with Firefox. I don't know why.