We would like to mail some of our chicks out to a family member in about a week. As I’ve never shipped before, I’m nervous. I have 4 chicks that will be 3 weeks old at the point of shipping and 1 that will be 10 days old. I still have a box that I received 8 chicks in. Thought of either using that or getting a cat shipping box from the pet store and shipping them from here 2-day express. Any advice on keeping them warm and what to put into the box with them? Or should I be waiting until they are at least a month old before shipping them? Thank you for any insights you have to offer.