Note that Jesus does not address Mary as “mother” but instead as “woman.”  The latter term is not one of disrespect; it is the same one He uses toward her from the cross in John 19:26, but it is very unusual for a son to address his mother as “woman.”  It is neither a Greek nor a Hebrew custom.  Jesus did this on purpose and probably to show her that there was now, after His baptism and the beginning of his ministry, a new relationship between them.  He is no longer the “son of Mary” but is now the “Son of man.” See John 1:51, Mat 12:46-50.

John 19:26  When Jesus saw his mother there, and the disciple whom he loved standing near by, he said to his mother, “Dear woman, here is your son,”

John 1:51  He then added, “I tell you the truth, you shall see heaven open, and the angels of God ascending and descending on the Son of Man.”

Matt 12:46-50 While Jesus was still talking to the crowd, his mother and brothers stood outside, wanting to speak to him.  Someone told him, “Your mother and brothers are standing outside, wanting to speak to you.”  He replied to him, “Who is my mother, and who are my brothers?” Pointing to his disciples, he said, “Here are my mother and my brothers. For whoever does the will of my Father in heaven is my brother and sister and mother.”

Mary, on the other hand, does not recognize this new relationship.  She is requesting His assistance based on her relationship as His mother, but her maternal relationship cannot be placed in connection to His work. There is a similarity between her misunderstanding here and the incident in the Temple when Jesus was 12 years old. Luke 2:48-50

Luke 2:48-50  When his parents saw him, they were astonished. His mother said to him, “Son, why have you treated us like this? Your father and I have been anxiously searching for you.”  “Why were you searching for me?” he asked. “Didn’t you know I had to be in my Father’s house?” But they did not understand what he was saying to them.

“Woman, what have I to do with thee?” (KJV) is translated by Barclay as, “Lady, let me handle this in my own way.”

“My time has not yet come” means “it is not yet time for me to act.”