You are advised to complete your applications as early as possible but within the guidelines of each school. Mid-October through November is usually ideal, especially for the more competitive schools. Most schools process applications on a rolling admission basis and begin offering acceptances well before their published deadlines. Therefore, it is best to file an application no later than early December if possible. Be aware that after a law school receives your application, it could take at least two additional weeks for them to request and receive your CAS report from LSAC.
Many schools have two published deadlines, an “application” deadline and a “completed application: deadline. The Application deadline usually only requires your application form and application feel. For the Completed Application deadline, your application is complete only when all information is received: application form and fee, personal statement, CAS report with a valid LSAT score, recommendations, and anything else the school requests. It is your responsibility to make sure your file is complete at each school.
The evaluation of applications varies from school to school. Many schools utilize an admissions index formula that combines LSAT score and GPA information. A few schools make most decisions solely on numbers (GPA and LSAT), others have no numerical cutoffs and scrutinize all aspects of the application. The majority fall somewhere in between, placing emphasis on subjective factors, but also making preliminary prescreening decisions based on numbers.
Once you receive an offer you will usually be asked to accept by a certain date and pay a deposit to hold your position in the class. Except for early admissions programs, the official policy of the Law School Admissions Council is that "law schools should permit applicants to choose, without penalty, among offers of admissions and financial aid until April 1." After April 1st you may have to forfeit your deposit if you change your mind about attending a school. If you receive multiple acceptances you should be courteous and inform schools of your decisions as soon as possible so those you decline can open up the seat for another applicant.
If you are placed on a waiting list at a school you may still have a decent chance of being accepted, but you may not hear until fall just before school starts. If you are very interested in the wait-list school it is usually acceptable to update your file if you feel you have something substantive to add, but check with the school first.