Talk to your high school guidance counselor now and let him/her know that you will probably have more applications than your classmates and that you will likely also have earlier deadlines. ASK, very politely, how the counselor wants to handle that. Also, mention that you may need to miss several days of school for auditions; clarify the school attendance policy and what you need to do to make sure those absences are excused. You may want to talk to the teachers you plan to ask for recommendations, too, and alert them that you’ll have early deadlines. Again, politely ASK how best to handle this. The advance warning and planning made things go much smoother for my second MT kid.
Others on this forum will have more recent information, but my memory (my second MT kid is graduating college in a month!) is that we aimed for all applications to be submitted and auditions scheduled by October 31. The guidance counselor was just getting revved up for everyone else’s application process to start! But we’d planned for it and the counselor was ready for us 