Microsoft is rolling out the first cumulative update build release for the Windows 10 Mobile Creators Update today which features one new fix that allows users to upgrade directly from the Anniversary Update to the Creators Update. The release of today's new build is further confirmation that build 15063 is indeed the final build that will be rolling out to the public in April.
Right now, build 15063.2 is only available in the Fast ring for Mobile users, as it contains a single fix for Mobile only. We assume it'll roll out to Slow, and the Release Preview ring pretty soon as this is the build that allows upgrades from the Anniversary Update. It's unknown when we'll see our first cumulative update for the Creators Update reach Insiders on desktop, but I'm willing to be it'll be soon.
Microsoft is now on path to general availability of the Windows 10 Creators Update, after several months of development and releasing pre-release builds to Insiders. Over the next couple weeks, Insiders should receive several new cumulative updates for both PC and Mobile via the Fast, Slow and Release Preview rings before the Creators Update rolls out to the public.