78 Matrimony is normally to be celebrated within the Mass, after the reading of the gospel and the homily, and before "the prayer of the faithful." The prayer for the bride, duly amended to remind both spouses of their equal obligation to remain faithful to each other, may be said in the mother tongue. But if the sacrament of matrimony is celebrated apart from Mass, the epistle and gospel from the nuptial Mass are to be read at the beginning of the rite, and the blessing should always be given to the spouses.
Source: Sacrosanctum Concilium (Vatican.va)