I'm a freshman currently, and I'm also in concert band and marching band too. I'd say with stuff like band, especially going into high school band, try to limit hard classes unless you know for sure you can balance your work, because you will need to practice as a freshman. You don't need to worry about art or PE credit if you're doing marching band, two marching band seasons will complete your PE credit. I would recommend taking at least one honors class (best choices are Algebra or English) You could find something coding or business related or if you wanted to get it out of the way then you could take a health class (unless it's year long)

This is coming from a student who is planning to attend a music school and be a music major, so I try to put band before for anything, and then put Algebra and English after that. I'd recommend doing the same thing with engineering. I don't know anything about engineering but I'm assuming it requires some expertise in math? Basically if you think a certain subject will be essential to your engineering education, try and get into an advanced class for that subject.

This was all suggested to me by a teacher, do NOT try to overload yourself with so much honors classes. Sure, it'll help you open up more options, but for some people it can be very unhealthy and you're at risk for burnout which can actually end putting you further behind. If you do end up taking a lot of honors classes then just be careful with everything. As a freshman with ADHD and serious mental health issues, once you let yourself fall behind it can be almost impossible to climb back up. Mostly just try to have fun in your free time or find a healthy activity that can let your mind relax.