At what precise moment should I cease to look at what is on the altar as bread/wine and rather as the body/blood of Christ?
Is it when the priest makes the sign of the cross over the gifts, “this is my body/blood”, or at the elevation? or something else entirely?
The Churches of both West (Catholic) and East have different but complimentary versions. The moment of Consecration in the Catholic Mass must occur when the Priest offers those same words as did Jesus. This is the time when the Holy Spirit under instructions from the Heavenly Father does His thing by changing the species of bread and wine into the Resurrected Jesus Christ. All of what the priest does within the authority given to him is to offer the prayer and words so as to effect the change. The change is always done by God. Since there is hardly any mention of the operation of the Holy Spirit in effecting the change in the Catholic Mass, the Catholic Church would mention that the change occurs precisely when the priest elevates both bread and wine. The Holy Spirit oddly is only mentioned at a certain time at the Consecration prayer. The Eastern Churches put more emphasis on the operation of the Holy Spirit to effect the change and in their Consecration prayers the Holy Spirit is even asked to come down from the Father to do His Work. Listen to the prayers which is contained in the Eastern Orthodox Divine Liturgy which is the same as the Catholic Mass.
At the Altar the Sub-Deacons and Altar Servers all prostrate before the Holy Gifts as they prepare for the coming of the Holy Spirit.
Priest: Again we offer unto thee this reasonable and unbloody service, and beseech thee and pray thee and supplicate thee: send down the Holy Spirit upon us and upon these Gifts here spread forth:
(The Priest signs the Holy Bread with the sign of the Cross saying
And make this bread the Precious Body of thy Christ;
People: Amen!
(The Priest makes the sign of the Cross over the Chalice saying
And that which is in the cup, the most Precious Blood of thy Christ;
People: Amen!
(The Priest makes the sign of the Cross over both the Holy Gifts saying

Changing them by the Holy Spirit: (Here everyone says) Amen, Amen, Amen!
Now the priests and Deacons join with the rest to prostrate before the Holy Gifts which are now have become the living Resurrected Lord Jesus Christ. They spend some moments in this act of adoration.
Here you can see where the Eastern Orthodox Church places the moment of Consecration at. In both Churches while the Eastern Churches describes precisely the role of which the Holy Spirit makes it is the same as it contained within the Catholic Mass. The whole of the Trinity is at work to give us this salvation this work of their love.