@shiftdev - The order in which UMD receives application material is not important, as long as everything is received. The following link provides information about submitting application documents, including LORs
http://www.admissions.umd.edu/apply/submittingdocuments.php.
You should also use UMD’s Document Tracker to verify that all required documents were received…
I strongly encourage you to have all application material submitted by the Priority Deadline (Nov 1) for the reasons spelled out by @maryversity in the following thread.
Good Luck