Where do you live in the USA? Many shippers in the northern US will not ship in late fall and winter months. Live fish should be shipped overnight express.
I would never attempt to ship fish this time of year (Thanksgiving- Christmas) as deliveries are just to unreliable as a result of all the package deliveries. Shipping plants might be OK, but shipping fish is just too risky.
If they do survive the journey, be sure to quarantine them as I suspect they will have some type of disease from the stress of the transit. There will be a buildup of
ammonia in the bag, so do not get any of the water into your tank. Acclimate the temperature, but as soon as you open the bag, get them into the quarantine tank. As soon as oxygen gets into the bag, the
pH will go up and the ammonium ion will turn to ammonia, killing the fish if you do not act quick enough. This is not the right situation for drip acclimation.