Google’s John Mueller confirmed yesterday in a hangout at the 15:38 mark that Google is indeed testing the mobile first index in the live search results. He did not explain what percentage of searchers are seeing these live test results but I have to imagine it is really small. With this test, Google is not only looking to see how much it impacts the searchers and current rankings but they are also building new classifiers for debugging purposes.
John explained that these internal classifiers are designed to label which sites have equivalent desktop to mobile pages and which do not. This way they can see if there are any common problems they are noticing across the live web where they can communicate to webmasters what changes they need to make. These forms of communication can be done via blog posts, direct communication from Google, Search Console messages and other means.
John Mueller would not give a date on the release but he did say they are testing things.
Here is part of the transcript but watch the video above:
It is one of those things that we need to make sure that the changes we make actually work out well. We are creating some classifiers internally to make sure that the mobile pages are actually equivalent to the desktop pages and that sites donât see any negative effects from that switch. And those are things we need to test with real content, we canât just make up pages and say this is well kind of like a normal web page. We really have to see what happens when you run it with real content.
At some point there may be aspects [of the mobile first index rollout] that are more visible but like with a lot of search experiments, these are things that most people donât notice because in an ideal world, things should just work the same.
Forum discussion at YouTube.