What is our human potential? How long are we going to take to become enlightened? I don't know; it depends on your Kamma, I would imagine. It depends on the development of the Paramis, because this is our human potential. We may all have this human potential, but it is not equally realized in us; people have different levels. According to the Suttas, the Buddha was once asked, "Why is there inferiority or superiority in human beings? Why are beings not equal?" He said, "It is Kamma that differentiates people according to inferiority or superiority." So depending on our Kamma, our potential has been more realized than others or less realized than others.
A classic example is the one of the prince who killed his father to become king. Later on in his life, he was very unhappy. He went to the Buddha and listened to his discourse. Great confidence in the Buddha arose in him at that time, and he declared that he was going to become a lay follower for the rest of his life. The other people who were listening to the Buddha were very happy, because that would mean that all his subjects would have a better time and his tyranny would be ended. However, the Buddha expressed neither delight nor any other expression. After the king left, the Buddha was asked why, and, according to the story, he said that if the prince had not killed his father in order to become king, he would have become enlightened at that teaching. But because of his Kamma, he had to fulfill the Kammic results at that time. As a result, even though he had the potential to become enlightened at that time, his Kamma prevented it.