So Jesus tells some servants to fill six stone water jars -- the kind used by the Jews for ceremonial washing, each holding from twenty to thirty gallons -- with water. Then he tells them to draw some out and take it to banquet. The master of the banquet is very impressed with the quality of the wine.
John notes (as Mary must be telling him) that this is Jesus's first "sign." So this event takes place very early in, maybe even before, Jesus's ministry. This is also one of few stories in John that take place up north in Galilee rather than in Judea.
Most of the rest of the stories in John seem to begin with "Jesus and his disciples were on their way to Jerusalem for the passover when all of a sudden ..."
To me this seems to suggest that the writer is somebody who only sees Jesus when he comes down to Jerusalem for the passover.
Which would not be the apostle John, since he is with Jesus during all of Jesus's ministry in Galilee. But I'll try to keep an open mind as we proceed !!