Was it when you came from a place of knowing nothing?
So often when new information comes into our world we add it on to what we already know. In fact usually this is how we learn everything, on top of everything else. And so how can we learn something that is absent of our own previous beliefs and perceptions, I am not sure it is possible. But there is a way to help interpret what comes into your world. To do this is to form wisdom. If you don't is to be opinionated and judgemental.
When you presume you know something and have an opinion on it, you can be called knowledgeable. To be called wise you must accept both sides of the story, all aspects of the portrait and then come to a conclusion.
When you listen to another you must incorporate their belief into your own without rejecting it. Their belief is true to them. Your wisdom is made up of more than just your opinion. Present all the shades of grey or the rainbow and you can paint a fuller picture in anyones mind. Truth as we know evolves, as soon as you stop it is no longer truth, but an old belief.