My one and only suggestion to high school kids is that:

Take as many courses as you can, because after high school, knowledge will NOT be free.

this is something I figured out after grade 12.. Unfortunately I forgot to take data management, and ended up regretting it.

so take as many courses as you can, forget about the "spare periods"
also good thing your are taking AP courses, because in university, having early knowledge from AP courses helps ALOT.

I actually think data management is one of the most useful courses you can take in high school