Since God rested from work on the seventh day (Genesis 2:3), and Jesus only did what his Father would do (John 5:19), why would Jesus turn water into wine on the seventh day? The account of the miracle at the wedding of Cana begins at John 2:1, "And the third day there was a marriage in Cana of Galilee." Nowhere in the full story (verses 1- 11) is day of the week when Jesus actually performed this miracle given. Therefore, we cannot conclude Jesus actually turned water into wine on the seventh day.
However, Jesus did perform other miracles on the seventh day (our Saturday). In Luke 13:10-16, as Jesus was teaching in a synagogue on the Sabbath, Jesus healed a woman who had been sick for 18 years. When the synagogue official confronted Him because it was the Sabbath, Jesus taught them the principle that it was good to do good for others on the Sabbath.
Several times throughout his ministry, Jesus healed on the Sabbath. Each time when questioned by the Scribes and Pharisees, He gave a little more information. Matthew 12:11 (NIV), "He said to them, 'If any of you has a sheep and it falls into a pit on the Sabbath, will you not take hold of it and lift it out? How much more valuable is a person than a sheep! Therefore it is lawful to do good on the Sabbath.' "
Similarly, in Matthew 12:1-13, Mark 2:23-28 and Luke 6:1-5, Jesus' disciples were picking and eating some grain on the Sabbath because they were hungry. The Pharisees challenged Jesus with the same question: why was He allowing them to work on the Sabbath? Jesus explained that He was Lord of the Sabbath, and reminded them that both David and the priests broke the Sabbath and yet were innocent in God's eyes (Matthew 12:3-5).
Jesus was governed by the highest law of Love, which is the basis for all of God's laws (Matthew 22:37-39), and that is what he wants us to follow, as well.