Google Mobile First Index will not fully deploy until 2018 according to Google’s Gary Illyes. Google might be releasing Mobile-First Index in multiple batches Do not Freak Out! You still have time to get your site fully ready for Mobile-First Index. My recommendation is to really work on your site fully mobile ready right and don’t wait until when Google is turning the metrics on. We use mobile devices more frequently than using our desktop devices, meaning our clients are also doing the same using mobile devices more.
According to Gary Illyes, Google doesn’t want to roll out Mobile-First Index and affecting non-mobile friendly website unfairly. This doesn’t mean we should ignore that for now but rather strategising your mobile strategy from now on. Illyes also repeated mentioned Mobile-First Index, doesn’t mean desktop contents or site will no longer be ranked; merely, means the priority Google will look into Mobile contents first.