He got it in Nazareth. We know this because he had it by age twelve. Luke and Matthew together inform us that during the decade between leaving Egypt and attending his first Jerusalem Passover, Jesus' parents attended the spring festival every single year. That means Jesus was living there. If he had not traveled elsewhere before age twelve, and he had such wisdom from paying attention in something like 500 Sabbath meetings, then no one should think Jesus had to travel anywhere else for the next 1100 Sabbath meetings, or so, before his baptism by John.
John tells us that Jesus said he got all his teaching from the Father. Before that became directly mystical, it happened on Saturdays in the Synagogue. It happened because of a focus and an obsession that, evidently, he managed to keep totally private from the rest of the Jewish community in Nazareth. (That thought, again, needs to be held onto for some future post. For now we have merely accepted it, without attempting to explain it.)
This can probably all be accounted for by recalling the one scripture Jesus most certainly learned early in life, and the one he most certainly heard more often than all others. Hear, O Israel. The Lord your God is One. You should Love the Lord your God with all your heart and all your soul and all your might. An historical view of Jesus at age twelve, filtered through all that we can possibly reconstruct about the Nazareth Synagogue, tells us Jesus must have taken this scripture greatly to heart when he was still very young.
In our modern age of leisure, some kids give their entire self to a TV show, or to a baseball team, or to a friend, or to a famous musician. In first century Nazareth, ever since Jesus was a boy, He must have genuinely cared about his Father, God, more than he cared about anything else. He was not trying hard not to sin. He was simply, sincerely, in all of his ways, worshiping Him.
I'll say it again. The historical explanation of Jesus' life before age twelve must be that this common Jew cared about God to an uncommon degree.
Everything after age twelve until age thirty-four is a question for another series.
Maybe. :-)
The End (for now)
Series Update: The Nazareth Synagogue