[metmom]

The feast at the wedding in Cana testifies that Mary believed in Jesus, for it was she who told them to do whatever he said, knowing and believing that He was about to astonish them.

I don't read anything in the text that indicates that she knew how Jesus was going to deal with the situation.

Another possibility is that the wedding was for Mary's family and that somehow she was involved in providing the food. When the wine ran out, since Joseph is not mentioned much after Jesus' twelfth birthday and one can conclude that he died, Mary would have logically gone to Jesus as He was the oldest son. For all we know, and all the text implies, she could have just expected Him to send them out to buy more.

We know a miracle is coming because we have the advantage of hindsight. Looking at it from the perspective of being there, as it happened, there is no indicator that anyone knew a miracle was forthcoming.

[MHGinTN]

Nice try at rationalizing away the miraculous in the scene. But please, m’Lady, look at the whole scene not just the chronology which supports vagueness. We are being given the scene as the first ‘recorded’ Jesus miracle in the New Testament, but the miraculous was not a foreign thing to Mary. The Magnificat gives us a soaring scene of Mary's faith and the power thereof. Consider what must have been the thinking of the servants who brought the hand-washing jugs of water after Mary told them to do whatever He says ... The scene is one of Mary having a clue and setting the scene for what follows.