The source – youtube.com
During the last video meeting for webmasters Google employee John Mueller suggested that Google will fully switch to mobile-first indexing in the first half of 2022. That means the process will be complete by next July at the latest. Until recently, the company couldn't say anything specific about the timeline.
Mueller said that if a site is ready to transition, it will be switched to the new indexing type during the next go-round. One thing to keep in mind is that the search engine is moving the remaining sites in groups, not one at a time.