"It's not that when I say the words of Jesus that it 'magically' then is the body and blood of Christ. It is when you receive the Bread and the Wine that he is truly present for you."
From what I've seen, this seems to be the understanding taught in the WELS churches. At one time, I discussed this with a pastor on the WELS Q&A site, and he deleted my post for my reference to "black robe Lutheranism." But anyways, back to the point...
Lutherans seem to be reluctant to say the "when and where" of the presence of Christ's body and blood in the Lord's Supper, other than that old adage of Luther, "we receive it in the mouth." This fear of peering too much into the mystery is very understandable, considering the overly-speculative nature of the scholastic doctrine. Yet, although Luther's words here are a helpful confession, we should not understand this as some doctrinal lowest common denominator. Christ says through the tongue and vocal cords of the Pastor, "This is My Body," not, "This will be my body when you receive it." As Augustine said, "The Word comes to the element; and so there is a sacrament." Luther said he had never said anything better (of course, he says this concerning a few of his statements). So then it is when the Word of God comes to the element that the bread and wine become sacramentally united with the body and blood of Christ. This belief is evident in our traditional liturgical forms when we sing the "Agnus Dei" after the words of institution. The "Agnus Dei" is a hymn of Eucharistic adoration, which is why we never sing it before the words of institution/the consecration, or after the reception of the Lord's body and blood.
The Word of God, which is the chief thing in the sacrament of holy communion, declares the bread and wine is the body and blood of Christ. It's ontological and not "essential" or "substantial," y'all; It just is! Is cannot be a "will be" without resorting to some Aristotelian notion of "essence" or some other bit of "specious reasoning." When you hear the words: "This is my body" and "This is my blood," know that Christ does not lie. Adore him... no matter what the explanations attached to your little blue LCMS Small Catechism or the "progressive" liturgists tell you.
"If any one says that the flesh of our Lord as that of a man is inadorable, and is not to be worshiped as the flesh of the Lord and God, him the Holy Catholic Church anathematizes." -Cyril of Alexandria as quoted in the "Catalog of Testimonies"