It depends.
There's things that I don't care or don't even remember.
I usually don't keep in mind the first times unless it's very important for me (I guess first kiss would be).
For me the first time is more stressful than memorable.
As I'm shy, I tend to fear any new situations (meeting someone for the first time, talking to a new person, going into a shop for the first time, etc.)
Once it's done, I'm more "used to it". It's a past situation, but it still needs time to adapt to that.
First car I was stressed to be alone, but now it's ok.
I'm still stressed when I go to a new road I don't know, but I don't keep track to all those things.