For most kids, it’s too early. If your kid is super interested, then I’d say do a casual visit if you’re in the area. I wouldn’t do a formal tour and I wouldn’t go out of your way. That said, college campuses are fun places to go for a walk and they often have concerts and events and that are open to the public, that would make a good opportunity to go on campus.
That said, there is a program in our area for low income, high achieving kids (mostly Latino in our area) in middle and high school. They do frequent college visits, even with the middle schoolers. But these kids, would be the first people in their families to attend college. They want to motivate these kids and let them know what opportunities are available. They also have workshops that teach the students how to apply for scholarships and financial aid, how to apply, how to write a good essay, etc. But again, these are kids whose parents probably have little to no knowledge about how the college process works.