St. Ildephonsus of Toledo (✝667 A.D.) called her the "sponsa Spiritus sancti" ("spouse of the Holy Ghost") in his Libellus de Corona Virginis or The Little Book on the Crown of the Virgin.
The Alexandrian (Coptic) Liturgy (Liturgy of St. Mark) also calls her the spouse of the Holy Ghost:
During Holy Week the following invocation is used morning and night:
Hail to thee, O spotless Dove, Spouse of the Holy Spirit, we pray thee to be mindful of us before thy Son.1031
—"Mary in the Eastern Liturgies" by Cuthbert Gumbinger, O.F.M.Cap., S.T.D., in Mariology (vol. 1) by Juniper B. Carol, O.F.M.; footnote 1031 references a journal article Devotion to Our Lady in the Coptic Rite by Alexander Amba in Eastern Churches Quarterly, Vol 7, April-June, 1948 page 408
The term "sponsa Christi" ("spouse of Christ") is more common, both in reference to Our Lady and to consecrated virgins (see Vizmanos, Christian Virgins in the Early Church).
St. Ephraim the Syrian (306-373) was one of the first to call the Virgin Mother Christ's bride, in Hymns on the Nativity hymn 11, where she says:
For I am Your sister, of the house of David the father of us Both. Again, I am Your Mother because of Your Conception, and Your Bride am I because of Your sanctification.
S. P. N. Ephrem Syri operum vol. 4, p. 327: "Equidem sum soror tua, quo amborum nostrorum proavus est David, et quo te concepi etiam mater, sponsa quoque per tuam sanctitatem", the first early Church father cited in Müller Mariologia p. 120