As Google plans to move all locales over to portable to begin with ordering .

The remaining 30% will be moved to mobile-fist indexing by September at the latest, as Google says that’s when all sites will be officially switched over.

Between now and September Google will continue to movie sites to mobile-first indexing as they become ready.

A sure sign that your site has been moved to mobile-first indexing is an increase in Googlebot’s crawling, particularly from the mobile smartphone user-agent.

You can also check in Search Console, where a site’s mobile-first indexing status is shown on the settings page as well as in the URL inspection tool.

Google’s guidance with regards to optimizing a site for mobile-first indexing remains the same. See: Google’s Mobile-First Indexing: Everything We Know (So Far).

Some major things to watch out for when optimizing for mobile-first indexing are:

  • On-page content is the same on mobile and desktop versions
  • Meta data is the same on both versions
  • Structured data is the same on both version

Google’s URL testing tool allows site owners to easily check both the desktop and mobile versions of a page. So you can ensure Google (and visitors) can see identical content on desktop and mobile.

Google specifically recommends not using separate mobile URLs (also known as “m-dot”) because they can cause “issues and confusion” for search engines and users. The gold standard for mobile-first indexing is responsive web design.