Once your application is submitted, you should make sure that it is received and complete at the law school. Some law schools will send you a postcard or (more likely) an email when your file is complete; others will notify you of missing information, but will not notify you of a completed file. Many law schools now offer a mechanism for checking this on their web page. You can also check when transcripts and recommendations were sent through the LSAC web page.
Just look under "Apply -- Report Status" on the left hand column, just below "LSAC Completed."
When you click on the tab, you'll see not only the report date, but whether the school is fully electronic ("Image"), or still gets reports sent snail-mail ("Paper"). This is important not only for the PC value of going green, but also for speed; imaging happens the day the report is requested; snail mail takes time.
If you are notified that any piece of your file is missing, follow up on it immediately. If you have provided incomplete information, send the required data, along with a brief apology for your omission. If someone else has failed to send the data, contact them, stressing the urgency of your need. Call back in a week to make sure the information was sent; call the law school a week later to find out if it was received.
The details of tracking applications may seem petty, but once or twice a year a client reports to me that a law school lost the application, or failed to make a decision because a piece of information was missing. Tracking your application may prevent you from being the person to whom this happens.
Knowing that LSAC sent your documents isn't the same as knowing that the school received them. Check each school's website to find out if they let you track applications online. If they don't and they don't send out post cards telling you that your file is complete, a phone call will be necessary.