Those beyond algebra 1 course paths should be left alone until your son reaches branching points. Definitely follow advice of your school teachers, GC because they know your son. I will never forget my gifted son’s problems with memorizing those arithmetic flash cards as a young first grader. He excelled in HS math and went on to an Honors degree in math at a top tier school. However- math is a brutal field (the math GRE has 900, not 800, as the top score) with top students from all over the world vying for top schools. I hated science as a HS freshman and chose chemistry for my undergrad major. A lot of changes in store- getting a solid foundation worthwhile instead of trying to push ahead just to be in the top classes.