The school year does not quite begin on the first day of school in August or September for teachers. Rather, it can take days or weeks prior to students starting to get the classroom in order. Factor in even more time to prepare lesson plans for the start of the year—especially if your school adopted new curriculum materials! Additionally, there are plenty of clerical things that a teacher may need to complete.
The classroom is where the majority of learning will happen. It is where you and your students spend countless hours. I encourage you to create a welcoming environment for you and your class. A first-day-of-school checklist for teachers will help.