As for you, Bethlehem, too little to be among the clans of Judah, from you One will go forth for me to be ruler in Israel.  His goings forth are from long ago, from the days of eternity.  Micah 5:2  written 600 b.c.  

In those days, Caesar Augustus issued a decree that a census should be taken of the entire Roman world. Everyone went to his own town to register so Joseph also went up from the town of Nazareth in Galilee to Bethlehem in Judea, the town of David, because he belonged to the house and line of David.  He went there to register with Mary who was pledged to be married to him and was expecting a child.  While they were there, the time came for the baby to be born and she gave birth to her firstborn, a son.  She wrapped him in cloths and placed him in a manger because there was no room for them in the inn.  There were shepherds living out in the fields nearby, keeping watch over their flocks at night.  An angel of the Lord appeared to them and the glory of the Lord shone around them and they were terrified. The angel said to them, "Do not be afraid. I bring you good news of great joy that will be for all the people. Today, in the town of David, a Savior has been born to you.  He is Christ the Lord. This will be a sign to you:  You will find a baby wrapped in cloths and lying in a manger." Suddenly, a great company of the heavenly host appeared with the angel praising God and saying, "Glory to God in the highest and on earth peace to men on whom his favor rests." When the angels had left them and gone into heaven, the shepherds said to one another, "Let's go to Bethlehem and see this thing that has happened which the Lord has told us about."  Luke 2:1-15

After Jesus was born in Bethlehem in Judea, during the time of King Herod, Magi from the east came to Jerusalem and asked, "Where is the one who has been born king of the Jews?  We saw his star in the east and have come to worship him."  When King Herod heard this he was disturbed and all Jerusalem with him. When he had called together all the people, chief priests and teachers of the law, he asked them where the Christ was to be born.  "In Bethlehem, in Judea," they replied.  Matthew 2:1-5

This prophecy makes it clear the Messiah's life will not begin with his birth.  He will have always existed.