So if you can not wait you should sign up to the forum / website go here to sign up:
Then go here and you can download the application and PC version here:
You still need to buy the unlock key from the Playstore to avoid the demo limitations like saving songs etc. But you can as well buy it now because if you are interested in making music with Android, Caustic 3 is a must have anyway and it will be cheaper now than after the proper release.
And you may even find a last bug to report!
Caustic unlock key
And a little Caustic 3 musical interlude