I made up a couple of flyers printed on SCREAMING neon yellow paper. In as large a type as I could fit, I put that live birds were going to be delivered on X date, my name, address, and three different contact numbers (home, work, cell).
I took the flyers to each post office (main distribution center, large town office, small town office) where the chicks might reasonably end up in the delivery chain, and specifically asked them to call me as soon as the chicks showed up.
Worked like a charm... we got a call 6:30 that Sunday night that the chicks were at the distribution center, and we picked them right up.
I definitely recommend an in-person visit to your post office if you're in a larger area, and a pre-printed paper with all the info they could ever need to contact you... it really helps!