5-6 months before submitting your college applications
Open a Common Application account. Fill out all the simple stuff you can complete now, like your personal details (address, etc.).
Look at the full applications for the colleges to which you’re planning to apply. Even though the applications for this admission cycle may not yet be available, those from the previous cycle are. Applications change relatively little from year to year. Besides, the college essay topics are generally open-ended anyway.
Meet up with your potential recommenders (or speak with them via phone) about your college plans. Otherwise, email them. After they agree to write a recommendation letter, email them with a bulleted list of topics they might mention in the recommendation letter (and/or provide them with a printed copy). Give your résumé (list of extracurriculars) a brief look (more if you have the time) and make sure that it’s current, then give it to your recommenders as well (either email or hard copy).
Be sure to also provide your recommenders with a printed copy of the college’s recommendation letter form, since they’ll have to submit this along with the letter itself. The easier you make this for them, the sooner they’re likely to finish and submit it. (If you’re applying early, tell your recommenders that you’ll need the recommendation letter by August, as some schools will allow you to submit your application on September 1. The earlier you apply, the better).
Start to brainstorm at least a few college essay topics. Write a 300-word paragraph on each and determine which ones flow most naturally and feel the strongest. Get feedback from trusted friends and family, as well as your guidance counselor, on which topic is best.