A day after heading out to Insiders in the Fast ring, Windows 10 Mobile build 15063.2 is now rolling out to Slow ring Insiders. As we noted in the Fast ring release, this build is a minor cumulative update that only contains a single fix that allows users to upgrade straight from the Anniversary Update to the Creators Update.
This latest build is only available to Mobile Insiders, and it's not entirely clear when we'll see it make its way to Insiders on the desktop. However, with such a quick move from the Fast to Slow rings on Mobile, we wouldn't expect it to be long before it hits Release Preview. In fact, now that Microsoft has an April 11 release date set in stone, for the Creators Update, we're likely to see any new build releases spread at a relatively quick pace.