Country Gal - I'm in NE Ohio. According to the McMurray catalogue, Chicks hatched in April hatch on the week-end and should arrive at your post office on Monday.
I got my McMurray chicks last June. My chicks were hatched on a Saturday and arrived at the main post office hub on Sunday. An employee there called us and we were able to get the birds on Sunday.
If no one at your main post office hub calls you on Sunday, they should be at your local post office on Monday. I just didn't like the idea of our chicks sitting around the post office that extra day.
That said, I have noticed that this year some people have mentioned it is taking 2 to 3 days to get their chicks.
I would suggest you call not only your local post office, but also your main post office hub, to advise you are getting live chicks. McMurray will put your phone number on the outside of the box, so the post office should call you.
Good luck! And don't forget to share details after you get your chicks!
regards,
keljonma