It depends on your child, but I think this is fairly typical for firstborn children and matches my own experience with my son:
I would recommend starting to talk about colleges during sophomore year, maybe leave some guidebooks around for your child to read up on colleges a little, and then take them on visits starting during school vacations during junior year or the summer between sophomore and junior years. Earlier than that may put too much pressure on a child who still needs to explore high school and who may not yet be ready to take such a concrete step toward living away from home as actually visiting colleges. You also may not know yet at which colleges your child will be likely to have a chance of admission, since your child will not yet have completed even half of her high school classes. You need to know what you can afford and what your child will have a realistic shot at before starting the process, so she will not start dreaming about a college she definitely will not be able to attend.
By February of junior year, have your child compose a list of colleges to visit. Look up which of these colleges may favor on-campus interviews as a sign of demonstrated interest. Plan most of your visits around interview timelines. First visit colleges that do not give interviews or give them in the spring of junior year. Save until later colleges that provide on-campus interviews but will not allow them until June or later (i.e., for seniors only).
You need to schedule tours and especially interviews in advance. Set up tours, info sessions, interviews, and then hotels, about three months in advance of your visit, to make sure you can get the dates and times you want on weeklong trips of multiple colleges.
Personally, if you are willing to read a collegeâs website in depth to learn about it, I recommend skipping the boring info sessions and just doing tours and interviews. I know others on this site disagree, but that worked better for my family who always enjoyed tours but hated the info sessions that never seemed to teach my son anything he did not know from having read a lot about the college before the visit.
Whenever you visit a college, be sure to sign in with the admissions office so they know you were there.
If you have a low income and cannot afford to visit colleges, then early junior year, start researching programs at specific colleges that fly kids out to colleges and programs such as Posse and Questbridge.
(Many kids apply to college without visiting, or begin the process later, so if this plan sounds like too much or too soon for your family, no worries.)
The month of May of junior year is time to meet with your high school guidance counselor, prepare any brag sheets you high school requires, and ask teachers for recommendations for the following fall.
The actual application work begins at the start of August of senior year, when the Common App opens.
Good luck! It is a crazy stressful process, but it also is a fun time vacationing and exploring together as a family, and it is fun watching your child mature and discover what are her interests and priorities. Enjoy!