The Son has always existed, so has the Father. Father and Son are titles, something you don't seem to understand. They exist as Father and Son within the trinity, and not outside of it.
Isaiah 44:6 Thus saith the LORD the King of Israel, and his redeemer the LORD of hosts; I am the first, and I am the last; and beside me there is no God.
Notice how this verse refers to both the LORD the King of Israel, and his redeemer as God. Seems like God can fill more than one role at a time and still be God. Interesting, isn't it?
Rev 1:17 And when I saw him, I fell at his feet as dead. And he laid his right hand upon me, saying unto me, Fear not; I am the first and the last:
Rev 1:18 I [am] he that liveth, and was dead; and, behold, I am alive for evermore, Amen; and have the keys of hell and of death.
Notice that this is Jesus speaking and referring to himself as the first and the last. Same as God did in Isaiah 44:6. Fascinating, isn't it?