There is no reference in the Bible to what Jesus did between the ages of 12 when he was discussing religious matters with the elders and 30 or so when he appeared as a prophet, this is a recognized fact. All we know is that when Jesus came to preach in his home town Nazareth that while the people were not exactly welcoming they were amazed by the change, surely that is just Joseph the Carpenter’s son but how come he has all this knowledge? Jesus wryly remarked that “The only place a prophet isn’t honored is in his hometown and in his own house“.
So what happened in between we shall probably never know but there are wild theories ranging from going to India, to England (William Blake : And did those feet in ancient time, Walk upon England’s mountains green: And was the holy Lamb of God, On England’s pleasant pastures seen), to even North America!