In the USA, they use FedEx. If you create a FedEx account you can monitor inbound shipments.
Usually, you will find these pending well ahead of release. Accessories are usually 1 pound and the phone 2 pounds.
Also when reserving with a credit card there is usually a hold upon preordering. Make sure you see this AND check your order status within 24 hours. If the card rejects the hold for any reason, (Samsung) will CANCEL your order. This happened to me because I used an expired card. (duh) I did not check to find the order CANCELED until a few days later and the shipping date slipped. This was the S20 Ultra. I don't think these phones are going to sell out that fast (or at all) you know with what's going on in the world, right?
In any case, usually these FedEx shipments show up early. Typically they will start moving right around when the charge is placed on the card. When a shipper creates a shipment in their system and it posts to FedEx you will see it even though no package has been shipped. It just shows something is going on with your order. Sometimes you will see several tracking numbers with some getting canceled. Perfectly normal.
I suspect some activity by mid week (this week) and movement by the time next weekend is over. Some may get theirs a day or two early.
Apple likes to troll users by handing packages off to the courier with instructions NOT to deliver before (release date). So you see it scheduled for delivery on a Tuesday (release day Friday in this example) and when Tuesday comes the tracking is updated with instructions to hold until Friday. I hate that!
My LED wallet case already shipped and is supposed to arrive today. I had a pending charge on my CC that disappeared yesterday. I called CS and was told the order is still moving forward, but I am checking Order Status on Sammy's website every day. I'll probably see the charge back on the CC before I get the FedEx shipping notice.