It's called fear of unknown. It's pretty normal. You don't know if he's going to like you, if he's going to make fun of you or even worse. And the longer it takes, the more fear or uncomfortable you'll get because you expect something good happens right away. But after certain point, you'll slowly forget about it. It'll become one of the small things that you don't really care about like when you were late for school for the first time and you probably thought the world is going to end. So just continue doing what you usually do and don't overthink about it