To answer the question about His age of existence (John 8:57), Jesus claimed to be the eternal I AM in v.58: absolute, timeless existence just as Jehovah is in Psalm 90:2 and Ex. 3:14. In contrast to a created being, Abraham, who came into existence (genesthai from ginomai), the Son simply 'is': from everlasting to everlasting. The Jews knew what Jesus claimed and wanted to kill Him unlawfully in the next verse. This is simply obvious. Claiming to be an ancient created being (Arianism) is not a death penalty and claiming to be the predestined Messiah isn't either (Socinianism). Both are clear examples of eisegesis.

Jehovah said εγω ειμι ὁ ὢν – ego eimi ho ōn (I am THE BEING) in Ex. 3:14 (LXX). It's interesting that ho ōn (present active, singular verb of being) is applied exactly to the Son in John 1:18 and ōn is also applied to Him in 2Cor. 8:9 and Heb. 1:3 in contrast to aorist tenses (something happening or coming into being in time). This further support the absolute being of the Son.

What Jesus said in John 8:58 is even stronger than Him saying the exact phrase 'I am God.' The word for God/god is theos and it is applied to many different things in the Bible including false gods. Jesus didn't need to say that. John 8:58, Rev. 1:17-18 and 22:13 etc. are sufficient enough.

The Trinity is from the Bible:

'A Biblical Case for the Trinity in 5 minutes' : http://bit.ly/1TQ5awo
'The apostle John was a Trinitarian' : http://bit.ly/1UBBF03
'Demonstrating the eternal Son from Scripture': http://bit.ly/1X6Ak4u
'Three persons in one context' : http://bit.ly/1UPK28f
'Trinity proven from the Old Testament by Sam Shamoun' : http://bit.ly/1X9WrHi
'Does "Let Us Make Man" Prove the Trinity?' : http://bit.ly/1TUoFBw
'Debate: Trinity vs. Oneness (Smith vs. Ritchie)' : http://bit.ly/25uMkBi