The question is as simple as the title. I am simply wondering, ‘When is the earliest recorded date of this tradition?’
According to Gibbons:
the public religion of the Catholics was uniformly simple and spiritual; and the first notice of the use of pictures is in the censure of the council of Illiberis, three hundred years after the Christian aera. Under the successors of Constantine, in the peace and luxury of the triumphant church, the more prudent bishops condescended to indulge a visible superstition, for the benefit of the multitude; and, after the ruin of Paganism, they were no longer restrained by the apprehension of an odious parallel.
It appears that the creeping in of images was long before the schism that brought about the RC and EO traditions -- so though your question apparently concerns post-schism timeline, I hope this answer is relevant.
See also the Catholic Encyclopedia on the Council of Elvira/Elliberis/Illiberis for arguments on dates.
The oldest icon I can imagine would be the one written by St Luke of Our Lady holding the infant Jesus regardless of whether you give any merit to the tradition that it was indeed done by him who was undoubtably the most well aquatinted man in the early Church with the Blessed Virgin Mary, excepting maybe St John the Evangelist, it is certainly an old picture and has been in the keeping of the St Mary Major for a very long time (~1700 years)
As long as we're talking about using icons in worship and not worshiping icons: The very earliest written account of icons in general that I'm aware of comes in Eusebius' Ecclesiastical History written in the early 4th century before and during the reign of Constantine (it is regarded as the very first history of the Christian church ever written):
I do not think it right to pass by a narrative that also deserves to be recorded for posterity. They say that the woman who had an issue of blood, mentioned by the evangelists, and who obtained deliverance from her affliction by our Savior, was a native of this place and that her house is shown in the city and the wonderful monuments of our Savior's benefit to her are still remaining. At the gates of her house on an elevated stone, stands a brazen image of a woman on her bended knee with her hands stretched out before her like one entreating. Opposite to this there is another image of a man, erect, of the same materials, decently clad in a mantle ... and stretching out his hand to the woman. Before her feet and on the same pedestal, there is a certain strange plant growing, which rising as high as the hem of the brazen garment, is a kind of antidote to all kinds of diseases. This statue, they say, is a statue of Jesus Christ, and it has remained even until our times so that we ourselves saw it while tarrying in that city. It is not to be wondered at that those of the Gentiles who were anciently benefited by our Savior should have done these things. Since we have also seen representations of the apostles Peter and Paul and of Christ himself still preserved in paintings, it is probable that, according to a practice among the Gentiles, the ancients were accustomed to pay this kind of honor indiscriminately to those who were as savior or deliverers to them.
Note that Eusebius seems to dislike icons although records that God works miracles through the statue mentioned here.
The oldest archaeological evidence is in the Dura-Europas I believe. That Wiki article states that this is the earliest preserved Christian church known (at least until ISIS destroyed it) and that it did contain icons.
So, as far as we can tell, icons were present in at least some localities from the very beginning of the church's recorded history. As mentioned in another answer, St. Luke is regarded as the first iconographer in Eastern Orthodox and Roman Catholic tradition, but this Wikipedia page states that the first known reference to Luke writing the icon is found in the 5th century. Although I wouldn't endorse believing everything found in the church's tradition (especially stuff from the dark ages): I would also suggest 400 years is not too long to be fairly certain of where a painting comes from.