John 1 describes in some detail
Jesus calling his first five disciples -
Andrew, Simon, Philip,
Nathanael
and presumably John.
John 2 1-2 says that Jesus' mother was at the wedding and Jesus was there with his disciples. So there were six followers of Jesus at the wedding (his mother and five disciples), and six jars filled with the new wine.
This seems to be another one of John's 'sevens'. Jesus commanded the six jars to be filled with water at the wedding, and then turned the water into wine. In the same way Jesus filled his six followers (the number six can represent humanity) with the new wine of the Kingdom. He is the perfect seventh 'jar', from which all the other jars are filled.
The passage here forms a beautiful contrast with Jeremiah 13; 12-14 where people are also referred to as jars of wine. In the Jeremiah passage the people described were the prophets, priests and the kings who sat on David's throne, as well as all the people of Jerusalem. They were all sentenced to destruction.
At the wedding at Cana one man, who was a prophet, priest and the king who would sit on David's throne, filled jars with a wine of blessing instead of destruction. It was as if the old wine of God's judgement a ran out at the wedding, and was replaced with the new wine of His blessing.
I wonder if this, the first sign that Jesus did, set the pattern for the rest of Jesus' ministry - he filled the 12, then the 70, then the 3,000 at Pentecost. And these people, like the jars of new wine filled to the brim at the wedding, (John 2:7) went on to share the new wine they carried with others, spreading the gospel of the Kingdom far and wide.
Incidentally the amount of wine Jesus created (approximately 150 gallons) was enough to give 3,000 people a good measure. Could it be that Jesus was looking all the way to Pentecost when he created the wine?