According to a short and sweet post on the official Wizard101 expansion page, players are being encouraged to head to the public test realm to try out Celestia in the next 24 hours. According to the post, "if all goes well", the expansion may finally arrive on all servers as early as Wednesday, October 27th.
Test Realm Last Chance! We're on the home stretch and what you see in the Test Realm is almost ready to be moved in to the Live Game!
Please take the next 24 hours to madly test as much as you can in Celestia, and if all goes well, we'll be putting Celestia and all the other features up to the Live Game on Wednesday October 27th!
Read more here.