Playing a musical instrument is a talent that many colleges consider special, and applicants with special talents get special consideration, above and beyond those who do nothing in school but get good grades. A second language helps your college application. If possible, take it as a sophomore, when its score means nothing to your future, and you will be better prepared to score high on the later tests that are meaningful. The people who distribute merit scholarships choose their national semifinalists solely on scores from the PSAT taken as a junior, so definitely take the PSAT that year. The volume of your mail is an early indication of how desirable a college applicant you will be.
Colleges only recruit students they really want.
The more mail you get, the more colleges want you. The accomplishments you record in Grades 11 and 12 are the most significant portion of your high school record that you eventually send to colleges. College admissions officers are impressed by a record that improves each year. A strong finish after a slow start looks better than an excellent record in ninth and tenth grades that deteriorates in the later years, so make your last two high school years stand out. Then take the SAT again in the spring.