There's NO WAY!!! I would "give it a day or two" The longer you wait, the less chance you'll have getting it, if in fact they delivered it some where else. Too late to call them about it now...but I would check tracking in the AM..right around the time your PO Opens...if it's still showing out for delivery..or God forbid, delivered... CALL THEM. I had this happen to me...checked one morning and it was showing out for delivery...the mail came and No package...I called the PO right then...they were able to call the mail carrier on their Cell...about 20 minutes later the mail carrier was back at my house. Package had slipped down behind her seat. (I live in the sticks, and Mail Carriers use their own personal Vehicle to deliver mail) Of course, she probably would have seen it at the end of the day and brought it to me the next...but if she had delivered to the wrong house...chances are, if you would have called them as soon as your mail was delivered, she/he may could have tracked it down before some one else got it and opened it.
Best of luck! Keep us posted!!