Google announced the plan for mobile first indexing in late 2016 and in late 2017 Google began indexing a handful of sites using the content on the mobile version rather than the desktop.
We began developing mobile first sites in early 2017 to give our client’s sites the advantage of higher search engine rankings with their content rich mobile first sites.
Having a mobile-friendly website is no longer an after thought in development. Instead, it is our first thought in design and development.