There are so many variables to the questions you are posing as there are no concrete rules when it comes to recruiting.
As a general rule the pitchers, catchers, and stud position players are being asked to verbal early which can be in their sophomore or early in their junior year.
When a player gets to high school it is never too early for them to email a college coach and let them know they are interested in their particular school. Send them a schedule, attend their camp as most schools will at least give a kid a look if they show interest in their school. For example my daughter had her first unofficial visit the fall of her sophomore year in high school, and made several more before verballing after the fall of her junior year in high school, but I also know seniors that got deals done late like during the winter months as well. Again no real set in stone timeline as each school is a little different.
The best resource book out for recruiting is available thru the nfca website
www.nfca.org and is written by Kathy Aradi. Worth the investment, but also consider accelerating the time line she spells out since more and more coaches are recruiting at an earlier age.
Hope this at least helps point you in the right path.......