What words or concepts describe how something feels like/ is experienced like for the first time?

I can’t explain myself better than this, but I’m looking for something that describes a first impression, the experience of doing something new for the first time, specially something meaningful. For example, how you feel when you listen for the first time to your soon-to-be favorite song, or when you see a girl that you find extremely beautiful, but with a beauty that is different from all beauty you have seen.

Solution 1:

nascent TFD adj.

starting to grow or develop; being born

As in:

Los Angeles Times 2019 “He did this for many artists. It was his gift; a rare gift. He spotted and nurtured nascent talent and brought to their work a layered intelligence rooted in acute observation.”

nascent describes the birth or beginning of something, like a new experience, a trend, an idea, or an action.

Etymonline

From 1620s, "in the act of being born;" 1706 in the figurative sense
of "beginning to exist or grow, coming into being,"