Although MPC heavily advertises that you can order as few as 3 chicks, you have to read the fine print because the 3 min. is only is you live in a large city (from their website):
How to determine the best minimum for you:
Our smallest order size of 3 chicks applies to major cities only, such as Los Angeles, New York, Chicago, Miami, San Francisco, Boston, Seattle, Portland OR, etc., due to the speed with which they can be delivered. If you live within 30 minutes of a major city, the best minimum is 5 chicks. For any town or rural area that is more than 30 minutes from a major city, our minimum is 8 chicks. This is to protect the chicks due to increased time in transit. If you are ordering Bantams, we strongly recommend that you add two chicks to any of the above quantities. We love our babies too much to let anything happen to them!
IMO, with the crazy weather we are having in the US right now it would be a bad time to order chicks and expect them to all arrive healthy.
I myself would not even consider ordering bantam chicks in any amount before winter is at least on its way out.
The small heating pad that MPC adds to their boxes can only go so far in protecting the chicks from the weather.
Just MHO.