With the start of back to school, it's time to teach all of the routines and procedures that your students become experts of by the end of the year. It's amazing to think that the students come in without any knowledge of the basics - lining up, recess procedures, assembly behavior, etc. This is in addition to the personal routines that you need as a classroom teacher - morning routine, bathroom, end of day routine, etc.
It's true that your whole school year is established within the first couple of weeks. Being a teacher is exhausting!