Sense of "light around the head of a holy person or deity" first recorded 1640s.
FWIW, the 'halo' of the Sun was labelled LONG AFTER the term 'halo' was used to indicate the manifestation of the spirit of an individual. In the Bible, the halo concept dates back to OT Hebraic times, as a physical manifestation of the Holy Spirit. The Hebrews believed the head was the center of one's vitality, the site of the reproductive life-force (and NOT cognitive thought, which they believed occurred in the torso organs, eg the heart, lungs, etc).
Hence why the condition of one's spirit was indicated by the general appearance of the tissue of the head. They also thought that damaging one's head could harm the life-force inside (and also why they considered having sex as causing a loss of vitality; also why "eye for an eye" laws came about). The Greeks had a similar concept surrounding flamma, as indicating the status of one's genius, also contained inside the head, and even older references exist...
Here's info on the halo (plus how the life-force spirit relates to oil lamps, as used as a replacement for child-sacrifice in ancient Hebrew culture) from Onian's "The Origins on European Thought: About the Body, the Mind, the Soul"
The Holy Spirit became visible as fire—at Pentecost, ruah meant 'wind'; and the 'spirit' (ruah) of a man or of Yahweh was, as we saw, of this nature. So,'suddenly there came from heaven a sound as of the rushing of a mighty wind and it filled all the house where they were sitting and they saw tongues parting asunder (i.e. distributing themselves) like as of fire and it sat upon each of them and they were all filled with the Holy Spirit' (Acts ii, 2-4). It was the 'baptism with the Holy Spirit' (i, 5). According to Matthew (iii, 11) and Luke (iii, 16), John the Baptist had the same conception: 'I indeed baptise you with water unto repentance; but he that cometh after me...shall baptise you with the Holy Spirit and fire (ev Trvsujicrn ocyfcp KOCI irupi)'.
This can now be related to the belief we have already traced in the Talmud (Niddah 30 b: see p. 153, n. 1 with pp. 147 fF.): that when a child is in the womb, a light burns on its head, in which the life-soul ( ='spirit') is; that is, in a human being his own spirit is manifest as fire.
With this we related not only similar beliefs among other peoples but also the belief about Moses that when he came down from Mount Sinai, 'the skin of his face shone and they were afraid to come nigh him51 (Exod. xxxiv, 30). It was, apparently, his spirit manifest in power; but the spirit of Yahweh possessing one would naturally be conceived in the same form, as of fire. We can now better understand the 'glory', or halo. 2
2 See p. 167. In the New Testament, 56§oc * glory* is used of shining radiance as kabhodh ' glory' is in the Old. See e.g. Acts xxii, 11; Luke ix, 29~32> I Corinth, xv, 41. Paul speaks of himself and his fellows as ministers not, as Moses was, of death, the letter of the Law that killeth,but of the spirit of the living God that giveth life. Therefore they shine with glory not less than Moses: * If the ministration of death in letters, engraven on stones, came with glory so that the children of Israel could not look steadfastly upon the face of Moses for the glory of his face, how should not rather the ministration of the spirit be with glory?.. .We all with unveiled faces reflecting as a mirror the glory of the Lord are transformed into the same image from glory to glory even as from the spirit of the Lord (or "from the spirit which is the Lord" duo Kupiou TTV6V|JOCTOS) God, who said "Light shall shine out of darkness", hath shined in our hearts to give the light of the knowledge of the glory of God in the face of Jesus Christ' (II Corinth, iii, 7, 18; iv, 6). The 'glory', kabhodh, 86£a (LXX), of Yahweh was visible fire (Exod. xxiv, i6f.; Ezek. i, 27f., x, 4 etc.). Cf. Isaiah x, 16 with passages in which kabhodh is used apparently of the soul or spirit in a man, e.g. Gen. xlix, 6; Ps. vii, 5 and xvi, 9, in which last it is rendered by the LXX as ' tongue', yAcocraa.
An oil-lamp was put on their tombs by the Jews in the first centuries of our era to represent the spirit.3 The equation had been made long before in a way which grimly convinces of its reality. We saw that in the sacrifice it was the fat, which was identified with the 'spirit5, that was offered (pp. 287, 484f.). ' In the period contemporaneous with Egyptian rule in Canaan, deposits of lamps placed between two bowls begin to occur under the corners of thresholds of houses, in positions where formerly sacrificed infants were buried. It is clear that these are intended as substitutes for child-sacrifice. The lamp, the symbol of life, takes the place of the life of the child. Lamp and bowl deposits become increasingly frequent in the upper Canaanite and Israelite levels, and jar-burials [i.e. of infants] decrease in the same ratio, until, about the time of the Exile, jar-burials cease altogether and only lamp and bowl deposits remain.'1 The lamp is not just a 'symbol of life' but equivalent 'spirit', life-stuff, to serve instead (cf. p. 188, n. 3). This, which links the oil or life-fluid in a man with the spirit, with which, as we saw on very different evidence, it was identified in belief (pp. 189 ff.), and which links it with the flame, as which both oil and spirit could be manifest, also perhaps lies behind ' The spirit (rfshama) of a man is a lamp of Yahweh searching all the innermost parts of the belly (beten)\ Prov. xx, 27.
3 See for example Hastings, op. cit. xn, 144^.32-2