If Letters of Recommendation are received after the application deadline, the Law School Admission Council will typically not be able to timely match them to your personal application file. You can, however, contact an individual school to see if it has their own policies regarding accepting such letters (as certain schools even have their own forms for such LORs).
As a result, although it does not take the LSAC a long time to process the LORs (typically no more than two weeks or so), you should be sure to make sure your recommenders send them in by the deadline so that you don't run the risk of submitting an incomplete file.
Best of luck!
Alisa Greenstein | Veritas Prep Admissions Consultant | www.VeritasPrep.com/law