As per usual, there are other perspectives on all this. And again as usual, alternate perspectives on issues, especially this one, are not met with a lot of, um, popular acclaim. Here's the alternate perspective I have in mind (please indulge me):
You say that "His sole purpose in coming to earth was to make disciples and the sacrifice. He knew this."
Well, personally I don't think so. I think that the earth is only one of thousands of planets for which Christ is responsible (through him all things were made). And this one was in trouble. And it was his to retrieve this planet and put it and all who live on it back on track toward its original purpose - and his - living up to the will of the Father.
One of the many things he had to do while he was here was to terminate the rebellion on this planet. Something was not going to plan here, something sponsored by Lucifer, and it could not be allowed to go on. Additionally, it had been quite some time since any prophet or teacher of truth had been here to upstep mankind's understanding of the reality of the nature of God, and mankind was by then capable of understanding a great deal more of that divine nature than ever before.
Thus his purpose in coming here was very different from what's commonly accepted.
Before He could embark on his business of terminating the Lucifer Rebellion, of illuminating The Way, and of introducing a concept more clear and revealing of the nature and character of God, he obviously spent a great deal of time in first growing up, and then in getting to know about life as it was lived on this planet.
During the times of Jesus, Palestine was a major world crossroads. The Roman Empire was at high tide. Trade in the Empire was brisk. Merchants and their consignments were coming west from Asia and from the Indian sub-continent heading to Egypt and to Rome. Goods also traveled from Africa around the eastern end of the Mediterranean and then to Rome, Turkey and points beyond. And of course from the west, from Gaul, Rome, Greece, & what's now called the Balkan States came the flow of goods in the opposite direction. Palestine was not only a crossroads, but a melting pot of sorts. People from all over the world were coming through and living in the Levant. What better place for Jesus to get to know a wide cross section of mankind than Palestine, the world crossroads?
We are pretty sure Jesus was a carpenter. And if the usual progression of things held true, Joseph was a carpenter as well and taught his son his trade. If Joseph's disappearance was due to his death, then Jesus as the oldest would have had a responsibility to care for his widowed mother and his brothers and sisters in the flesh. I can't imagine him letting this responsibility slide. So Jesus would have been in his middle to late twenties (from what we can surmise) before the youngest child would have been considered raised, and independant, and his mother's future secured.
If Jesus was "tested in all things" then he would have been tested in raising a family, working a job, paying a mortgage, learning a skill, and on and on and on.
So there are many, many reasons why Jesus didn't begin his ministry until his third decade.
We have no way of knowing what Jesus did. He may have gone to Rome. There is nothing to indicate otherwise. He may have gone to India, to Egypt, to anywhere at all, getting to know the men and women of this planet. He surely went about his entire life "doing good."
And then, when the Father's time had come, he embarked on his ministry of disclosing to an ignorant world a higher and more beautiful concept of the loving nature and charming character of his Father and ours in heaven. And do you know what? There are millions upon millions of people on this planet who, claiming to be Christian, even to this very day two thousand years later, do not fully accept Jesus' revelation of that enlightened description of the nature and character of God. Oh well, the only way for a tadpole to grow into a frog is to live every moment loyally as a tadpole and all else takes care of itself. Even so, two thousand years seems a little long.
They insist (and Jehovah's Witnesses are the worst of the lot) in grafting the olden concepts of God onto Jesus message: Yes, God is Love, but do wrong and he's gonna getcha; God changes not, but bastards used not to be accepted in the congregation, now God accepts them - what happened? God used to claim the soul was in the blood and wanted it poured out in sacrifice. And now (except for some of Jesus messangers who didn't understand him either, and who were still teetering on the brink between Jesus' new teachings, and the old law code) God wasn't interested in the blood of sacrifices at all.
Jesus didn't come here to enlighten people about the nature and character of Jehovah. I'll bet the word Jehovah didn't escape his lips. He didn't come here to tell us about the olden, tribal, war god Jehovah of Armies because Jehovah isn't God. Jesus came here to reveal a god of Love, the majestic being behind all creation. Jesus didn't come here to tell us all about a God to whom the smell of burning animals and their fat was a "restful odor." He came here to reveal an existential and eternal being whose perfection we are all to emulate: be you creature perfect as he is diety perfect. He didn't come here to reveal a God who would have the Hittites put to death down to the last man, woman, and child; but to reveal a gentle and compassionate God who knew and loved all his children without reference to their ignorance about him.
Jesus came here to reveal:
God to Man
Man to God
Man to himself
And he did all this, terminated the Lucifer Rebellion, and much, much more, before he was 35 years old.
And then he was gone.
And men have argued about him ever since. And it hasn't been helpful that several old men, men who didn't understand Jesus when he was standing right before them, wrote what they could remember of their experiences with him decades after his death. Nor did it help that a reformed pharisee who didn't know Jesus at all in the flesh took it upon himself to organize a religion ABOUT Jesus. It's been pretty obvious for two thousand years that what we needed was instruction in the Way of the religion OF Jesus.
Anyway, I have engaged here in a big runon sentence, so to speak. Obviously, I have spent quite some time in reflection and meditation about these things. There's just not many ways to comport the Jehovah of the OT, with the loving God revealed by Jesus. There's not many ways of reasoning about the Love of God while at the same time including such barbaric concepts as original sin, atonement, redemption, and all the rest.
There is a Truth out there concerning these matters. We need to strip away the accumulation of two thousand years of opaque accretions surrounding the Light of the Truth brought by Jesus; to remove this "bushel basket" from that light, and to allow it to illuminate us for the very first time.
And everyone on this board (well, you know) has made very good progress already in cleansing from their life one of the most ignorant, backwards and retrograde cults misrepresenting the releasing truths of Jesus and his life. And now, we're ready to step forward into the Light of a Higher Life.