Google’s John Mueller said this morning on a Google hangout at the 3:40 mark into the video that you can pretty clearly see if your site has been moved over to the mobile first index by looking at your log files…
Source: 9
More from my site
Google: Disavow Links File Needs To Be On Canonical Version For Manual Actions
Google: Things Looking Good For Mobile First Index
Google May Release Mobile First Index Slowly In Batches
Google Image Search Does Not Index Images From CSS
Google: Contact Information On A Web Site Is Not An Organic Ranking Signal
Google: URLs In Sitemap Used To Determine The Canonical URL
