Sadly, many companies illegally ship reptiles. Mostly it is "Don't ask, Don't tell". In my opinion, you should have had them not ship until Monday so the "weekend nightmare" could have been avoided. I am not blaming you for this, so dont' take it the wrong way
It is merely learning how to use hindsight before hindsight happens
Chalk it up to experience and a lesson learned.
Good luck with the baby boa, he should be fine if he is moving around now. Wait a week before attemptimg to feed him, but start him out on rat pinks, not mice. It will put more weight on him faster than the mice will (too much fur, not enough protein) without having to 'powerfeed'.