When to start preparing?

When is it an appropriate time to start planning for college? Sending out emails, asking questions, seeing requirements, seeing about scholarships, campus tours, etc. I really want to major in pediatrics and minor in neonatal. I was looking into JMU, UCLA, UNC Chapel Hill, or JHU. But the problem with all of those will be money because of out of state fees plus living fees. I thought of looking into like U of M or MSU because I won’t have out of state fees still will have living fees cause that’s to far of a drive every day but at least no extra fees. I am currently a sophomore in high school. When should I really start diving more into college planning and what do you believe the best college for pediatrics and neonatal is? Also what should I be really looking for, and asking? How should I prepare myself for college while still in high school?