I would disagree with the earlier is better unless as we say here you have something to tell them about. If your kid is as another post says a 6' throwing 80 or hitting bombs on high school fields then you have something to tell them about. If he is throwing 70, then wait until you have something to tell them about. You don't want them to take you off a list because you persisted too early which they will do and it is harder to get back on the list. Unless you are talking
I personally do not think you pursue your top schools until you are at least in high school or have something really special to show them. Unless you are going to kid's camp. Also remember you do not want to invest a lot of money going to camps and building relationships with the coaches if that is a dream school and the coaching merry go round throw you off. There are very few Mike Martin's who go somewhere and stay a long time anymore.
This is just my opinion and experience. When mine was on the varsity field as a freshman and had success, we began to send information to coaches because we had something to tell them. When it comes to Showcase ball, make sure your level of play is something to tell them about. There are many levels of play at middle school ball. Unless it is PG or equivalent, most college coaches are not interested in that information.