If you have a high school junior in your house this year, the time to sign up for college advising services with a private advisor is YESTERDAY. Too many parents wait until the fall of the senior year in high school to realize they either can't or don't want to manage the college process themselves. By that point, most of the people I know who are independent advisors are FULL. They can't take new advisees.
Aside from getting in to a college advisor practice, the practical reason to start in 9th, 10th or 11th grade is that many advisors offer a flat fee contract that does not increase cost if you start early. Imagine the advantage of a ninth grader fully understanding what he needs to do in student activities starting in freshman year and how well he has to do in school to get into the "cool" colleges. Too many freshmen think they can wait until their junior or senior year to get serious about grades or activities. By then it is too late.
Give serious thought now as to how you want the last years your child is at home to go. Do you want to fight about where he is going to college? Do you want to spend significant time nagging him to get tasks done and checking after him? Or do you want to have a third party, aware of what should be done, guiding him while still keeping you in the loop?
My email inbox is full of pleas this month from other advisors from accross the country asking if any colleagues have room for another senior. Most will say no. Give thought to this now and decide to do it on your own or hire a partner while you still can. Choosing an advisor early also means you can choose from a wider group of advisors in your area.
While the best advisors are busy year round, they are also happy to refer you to someone who has the experience with the type of student you have and with the goals of your student. The Higher Education Consultants Association is a great resource for finding an advisor in your community who can provide the help your family wants.