When did you realize that you've become a father?

The time when your child is born, may not be the time when you start feeling like a father. I mean, sure, label lag jata hai tab. Mubarakbaad, mithaiyan, salamiyan, wo sab ho jata hai. But ek proper realization zaroori nahi usi waqt ajae! The moment you start to REALLY feel like a father may be some time in the future when something particular happens. It can be anything. What was that moment for you?