The company announced that the feature will begin testing among U.S. users on March 18, but Community Notes won't yet appear to the public while in beta testing. Once they do show

Meta will begin testing its X-style Community Notes starting March 18th. The feature will roll out on Facebook, Instagram, and Threads in the US – but Meta won’t publicly publish the notes to start as it tests the Community Notes writing and rating system.

Meta will start testing its Community Notes model, with which it's replacing human fact checkers, on Facebook, Instagram and Threads in the US on March 18. Notes won't appear publicly on posts right away.