Google is going to roll out the mobile first index very soon and those who haven’t opted for
responsive websites should go for it as soon as possible. Also, if this the first time you have heard about “Mobile first index” then leave everything and just click here to know the details about this major shift. There have been two shifts in preparation:

Search Console Reports

Google often does not openly discuss upcoming changes but this time they are doing whatever
they can in order to inform people about the major shift. John Muller recently said that those who are going to get impacted by the shift will receive warning and guidelines within their GoogleSearch Console accounts so that they can resolve the issues before the changes take place.
“We will inform people when we get closer when we actually have a date, so there is sufficient
time for people to kind of resolve issues that they may need to resolve. We’ll try to also inform sites where we recognize issues, so if we recognize that maybe your mobile version doesn’t have all of the same content or markup that your desktop version has then we’ll try and let you know about that through Search Console as well, so that you kind of are aware of these issues and kind of have time to resolve them.”

New TestMySite Tool

Google has also introduced a new tool using which you can check the mobile friendliness of your website: https://testmysite.withgoogle.com. This new tool replaces the old search console mobile friendly tool.

When you enter your website’s URL, it displays your websites mobile friendliness and also sends you reports to your email stating what your website is lacking. Not only that, it also provides you with ideas on how you can improve it. Make sure the maximum use of it.