Help for Oath Letter

[pob6171]

Would anyone guide to as to when your online status changes to Oath Ceremony when should you normally receive the letter in the mail. I have already been waiting 7 days since my status online changed and I received the email. Should I start to get concerned in case the piece of letter got misplaced or mis-delivered? My DO is Mt Laurel NJ. Greatly appreciate any help.
Still the endless journey is not over yet.
Thanks A Million!