Congratulations! You have finally made it to the practicum experience in your undergrad education. I am sure you are full of excitement. The butterflies will probably begin the night before you go into the classroom to which you were assigned for the first time. Those butterflies will be there the first day of your student teaching assignment, the first day in your first teaching position, and probably your first day of school for years to come.
I noticed somewhere around year 16 or 17 I stopped getting the butterflies. It wasn't that I was any less excited. You can ask your aunt, I'm usually ready to get back in the classroom as August rolls around. (I love what I do) I'm not sure why it has stopped. Maybe I have been doing it so long, it no longer makes me nervous.
Thankfully, you have the type of personality that loves new experiences, loves challenges. I believe you have to be a bit of an adventurer to be a teacher. It doesn't matter if your classroom is the same, or the curriculum is the same, from year to year. Your students will not be. Even if you have the same set of students you had the year before, they will not be the same, they will have matured over the summer, hopefully : )
Your students are always changing; they are not static like totals on a spreadsheet. Due to this, you need to be adaptable, willing to change things up in order to reach your students. At times, it may be exhausting, difficult, and aggravating but when you see that the kid that you "pulled your hair out" in trying to think of ways to reach him/her finally "gets it", well, I can't even explain the joy and sense of accomplishment you will feel. It will allow you to see the effort was worth it and encourage you to struggle to reach the next "difficult" student.
Why do I love the first day of school?
It is a new beginning, a fresh start.
I get to work with people that have moved from colleagues to friends in my life.
It allows me to improve the faults in my lesson plans and their implementation.
It allows me to continue the practices that students enjoy and are effective.
But most of all
It brings into my life a new crop of students
Who will bring a smile to my face as I remember them in future years.
I love the first day of school, best wishes on yours,