Google’s advice to go responsive before mobile first indexing rollout
Google will roll out mobile first indexing in few months and recommends sites to go responsive or AMP before that.
Google supports a range of mobile implementations, but still recommends responsive or AMP over others.
It recommends following steps, if the sites are moving from m-dot to responsive:
Step 1: Get your AMP or responsive site ready.
Step 2: Put permanent 301 redirect from the old URLs to new AMP or responsive versions of pages one by one.
Step 3: Remove any mobile specific configurations such as HTTP header or redirects.
Step 4: Set up self referential canonicals (rel=canonical) on new AMP or responsive versions.
Google is making all the announcements before rolling out mobile first indexing so that sites and businesses don't see any fallout in rankings.
It may be a major task for sites to go responsive or AMP, but they don't have any choice, if they still want to attract the traffic from Google - the giant.