Yesterday, Microsoft released Windows 10 Mobile build 15063.2 to the Fast ring, which includes a fix that allows for an upgrade from the Anniversary Update. Today, that build is being promoted to the Slow ring.
While Fast ring Insiders only saw a single fix from the cumulative update, Slow ring users are getting a number of fixes, as 15063.2 replaces 15051 in the ring, so quite a bit has happened since then.
Build 15063 is the RTM build of the Windows 10 Creators Update, and that's the same across the board between PCs, phones, HoloLens, Xbox One consoles, and anything else that's powered by Windows 10. In other words, if you want the Update early, it's not just a buggy preview anymore.
If you don't mind waiting, Microsoft announced today that the Creators Update will roll out to the general public beginning on April 11; however, it previously stated that it would be available to PCs first and other platforms later. The firm also released the Update for Xbox consoles to the general public today, which of course directly contradicts that last statement.
Microsoft hasn't provided a timeframe for how long it would be between when PC and phone users get it, but for version 1511, it was about four months, and by the Anniversary Update, it was just two weeks.