Good question! First of all, don't forget that our chicks can arrive any day from Tuesday through Thursday of the week they are shipped--it just depends on how quickly the post office delivers to your area. So have your brooder and everything prepared by Monday (so you don't have to scramble)... but don't worry if it's a Tuesday or Wednesday and your chicks haven't arrived yet.
As to how you'll know they're at the post office, in our experience most POs ask customers to pick up their peeping packages right at the post office.
Your phone number will be printed on the box so they will know how to reach you when it arrives. (When you place your order, be sure to provide us with the phone number you want them to use to notify you.) However, it's also important to get in touch with your post office before the chicks arrive so they can fill you in on any policies relating to how they handle chick deliveries locally. Some deliver chicks right to your door instead of asking you to pick them up, for example. You'll want to know what to expect from your local post office so you can be prepared!
Losses are rare, but they do occur, so we recommend that if you have children, they are not around when you open the package. If you do experience any losses, please let us know within 48 hours--your birds have a 100% live arrival guarantee. See the related questions below for more information.