From what I've heard, when it comes to Power 5 schools, the earliest a HC/RC will have a true educated guess as to if a player can contribute for them is when they see them as rising Seniors on the biggest Showcase/Tournament diamonds competing against top Power 5 recruits and potential MLB draft picks. Anything earlier than that is mere guesswork and projection.
This is an important element that many parents of early commits miss in a huge way. It really depends on the early commit's personality. Will they continue to work just as hard after they commit? And even if they work really hard, will the talent potential simply top out? For so many, the goal is to "get to college ball". The college coaches are looking for players whose goal is to excel at the college level and help win championships. Big difference.
You can commit as an 8th Grader, 9th Grader, whatever, but if you show up at Jupiter or Kernels or Area Code, WWBA etc in the summer before your Senior year and you can't hit the 90+ mph pitchers or you get raked on by future SEC/ACC hitters, your early commit is as valuable as a hill of beans.