Gavin Sykes's Video

At least by the 6th century, icons were viewed as being means for saints to intercede on behalf of others. Theodor and Agnostes is said to have claimed that an icon of Mary was sent to the Empress Polkeria in 438. Gavin Sykes comes from the 7th century involving Pope Saint Gregory the Great. In any case, I don't disagree with the section in Gavin's video which summarizes the scholars who study this issue  as settling on the 6th and 7th centuriesBeing the time when the veneration of icons becomes more established in church history.