THANK YOU EVERYBODY!!
Got mine for 8/20!
I tried the first link on my phone and was waiting for about 30 minutes, then decided to keep that open and try trying the second (AP holder) link on my tablet. That one worked right away, and the other one actually opened up for me while I was choosing my date!
Also funny: As soon as I finished registering and got to the “you will receive an email confirmation” page, I got an email alert… It was from the Passholder Program, inviting me to register for the preview. I had to go to my spam folder to find the actual confirmation.