Murphy's Law: The less you really want a particular job, the higher the chance that you will get it. Anyway, actually the first day is probably the easiest as you are not expected to know that much about your job -- Yet! FYI: Don't let them see how nervous you really are.
It doesn't happen to me. Interviews are always more nerve racking for me.
Yes. The interview is easy. Cake walk. Now, starting the job I have to deliver on all those things I said I could do in the interview, all while learning the ropes. :/ I'm a much better interviewer than employee lol but hey, you get used to it after like a week of the routine.