Depends on whether your letter carrier is diligent and competent or not. The guy in my area is. Package comes into P. O., is sorted into his route, he delivers next working day.
But before him I had a letter carrier who would delay, leaving items for the sub to deliver. Even a magazine would be delayed 7-10 days after publisher sent it to my post office.
My letter carrier admits he knows some of his co-workers intentionally let packages sit for days, hoping it'll be taken care of during their day off.
I'll bet that is happening all over the country.