I don't think the USPS tracking/notification system is very reliable. You might be surprised....
Very unreliable.
I'm waiting for a shipment and just got notification that it arrived at the sorting facility in Vegas at 0100, was moved to the Henderson PO at 0600, all about 15 minutes ago.
It's all about when they scan and update, which they aren't always Johnny on the spot with. I've found the ominous orange slip in my door, waited a day, and picked up my package the next day... only to get an update the FOLLOWING day.
I said in another
thread that they sent me nasty notices to "Pick up packagde by Xdate or it will be returned to sender" days after I picked it up.
So keep the faith.
Just another note: If you call your Post Office with the tracking number, they can tell you if its there or if its out before you get the day old updates.