I always looked forward to the first day of school. I enjoyed getting caught up with people I hadn't seen since the previous school year ended, and it was reassuring to know that I wouldn't be given any insurmountable assignment that day. This was especially true in high school orchestra class. Per the director, we'd begin each school year with a free-for-all of introductions,"so the old get to know the new and vice versa." The director would relay some thoughts about the year ahead, and we'd spend the rest of the hour chatting and introducing ourselves. At the end of the hour, Mr. D. would tell the class, "Bring your horn tomorrow, and we'll start making some noise right away."
I always thought that was a good, matter-of-fact way to tell the string orchestra, "We'll get down to business tomorrow," while using the word "horn" metaphorically.