When does the Sacrifice during the Mass? Is it the whole Mass? Is it at the words of consecration? Thanks and God bless.
The Liturgy of the Eucharist.
“In the institution narrative, the power of the words and the action of Christ, and the power of the Holy Spirit, make sacramentally present under the species of bread and wine Christ’s body and blood, his sacrifice offered on the cross once for all.” (CCC 1353)
The sacrifice begins on Calvary where the Victim is killed. Then the Flesh and Blood are brought miraculously to the altar, where they are offered to God. (This perfectly continues the practice of the Temple sacrifice in Jerusalem, where the victim was killed away from the altar, and then the flesh and blood were brought to the priest to be formally offered to God.) The Consecration is the bringing of the Flesh and Blood to the altar. The Eucharistic Prayer is the offering to God of the sacrifice. As in the Temple sacrifice, the formal Sacrifice in Holy Mass is complete when the priest consumes the Host.
So, the parts of the Mass that are formally parts of the Sacrifice begin with the words of consecration, when the Flesh and Blood of the Victim are made present on the altar. The sacrifice continues through the Eucharistic Prayer, the Our Father, the Agnus Dei, and ends when the priest consumes the Host and drinks the Blood of Christ to begin the Communion Rite.
Communion is also organically connected to the Sacrifice, though it is not part of the formal Sacrifice itself. In the Temple sacrifice a communal meal often followed the sacrifice proper. After the appropriate parts of the victim were offered to God by pouring of the blood and burning of the fat and other parts, a portion of the flesh was given to the priests, and the remainder of the meat was returned to the family on whose behalf the sacrifice had been offered. The family and their friends then feasted upon the remainder of the consecrated meat.
For some details of the Jewish practice of the Temple sacrifice see jewfaq.org/qorbanot.htm.
For the separation of the slaughter of the victim from the offering on the altar see e.g. Leviticus 1:1-13.
Pax Christi vobiscum.