I guess I can agree with the "sophmore is a bit early" rationale,
as if you send introductory letter(s) now you'll be entered into their database & begin receiving camp brochures, school brochures, general and academic info promoting the colleges,
AND WITH ... baseball questionairs to fill out.
multiply that by the dozen or so schools you contact & just sorting and organizing all the correspondence can become a real headache, but - a good headache
never do today what you can put off till
tomorrow or next year.

btw, as you say non-athletes begin college contacts early, there is every reason for athletes to do the same.
good luck
.