Every year I meet people who are in their first real academic gig...
Since I'm at teaching focused schools, so are they -- Naturally, I remember my first weeks of school and the lessons I learned more or less the hard way.
1) Teaching takes a lot of energy -- especially the first week or two. This gets better, as the classes get to know you and vice versa.
2) Things don't always go as you'd planned -- either the discussion is shorter or longer than you thought -- that's normal.
3) Some of your students are idiots --- this becomes clear early in the semester.
4) Some of your students are brilliant -- this becomes clear a bit later -- and the waiting time between 3) and 4) can be difficult at best.
5) No matter what you do, your students will surprise you. That's what is fun about teaching. If you are lucky, you'll have a few students in every section that will read the assignments and ask good questions. They'll help you see the familiar works in a new way.
6) If it isn't too late, put presentations at the end of the semester. Each presentation you hear and assess in class is a paper you don't have to read before you start your Winter Break!