By and large, I put myself out there at the start. I don't have much of a problem with who I am, I don't really feel a need to be anything different than who I am, and so I'm not really embarrassed about it or anything. But at the same time, there's some things that are too painful or too embarrassing that have happened to me and influenced the way I am, and those are things that I don't share until someone gets through the relevant walls.
Think of it in terms of Constantinople's walls from Byzantium:
They had an intricate series of walls that were almost completely impenetrable. You had to break down one series only to get to the next, and they were multiple layers of walls thick. Someone has to work their way through them by gaining my trust. I, and it's an INFP tendency, move slow in relationships mostly because the person has to work their way through one wall to get to one thing, but not bump against another wall in the process.
It's not that I think something should remain secret, it's just that it's something painful to me that I don't want everyone knowing about.
That's especially true with people I don't know that well. The outer layers of average friendship are pretty easy to get into, but I don't walk around talking about myself to people who I don't know.
Does any of that answer your question?