There is an easy way to check all of this - that is - if you purchased your phone through Apple or know that your carrier will be using UPS.
You can sign up for "My UPS" service (aka "UPS My Choice"), which will inform you (depending how you set it) of any shipments headed your way. Please see ...
UPS My Choice - Home Delivery on Your Schedule
I have this service. My 6 plus was ordered from Apple inc. at 12:40 PDT on opening night (64GB, Verizon, Silver). I also have "my UPS" service, as we receive a lot of packages here. Now My UPS has not yet sent me a notice because they have not yet received the phone. Apple still lists mine as "preparing for shipment". However, when I log in to My UPS, I can find that UPS expects a shipment to me from Apple for delivery on Friday 9/19.
From what I have read, Apple is shipping millions of iPhones via private carrier from China to the USA - and has been for a while. My UPS says that a "shipping label has been created" and it will ship the phone to me by UPS overnight to deliver on 9/19. It also says that my phone will come from Apple in "Rialto California." It may have already arrived (likely not), but it clearly wont be shipped from Rialto CA until Thursday. I live in the San Francisco Bay Area. Either way, the shipment is scheduled and is likely on some cargo plane from China as we speak. That means UPS won't acknowledge it has the phone until probably Thursday.
Anyone can sign up for MY UPS service. You can find lots of stuff there that the vendors do not tell you. Good luck.