High School Transcripts

Hey Everyone!
I finished my application for BU and submitted it last week. The problem is my county is extremely back-logged in sending transcripts so I decided to mail a sealed and signed transcript myself. Does the transcript have to be sent in by Jan 4 (application deadline) or should it be postmarked by Jan 4th to recieve consideration for admission. By the way I am a freshman applicant. Thank you for your time!

That is not an official transcript if it has been in your possession.