How do you know if a snake is stressed or not?
Just because you picked it up and it isn't fighting being held is not a reliable indicator. Balls are fairly docile. It's not that they like being held - as a rule, they just aren't programmed to fight back against being handled.
Eating? Does the fact that's it's eating mean that it is not stressed? Does the fact that a snake doesn't eat always mean it IS stressed?
I see alot of justifications being tossed back and forth for messing with an animal shortly after bringing it home. When it comes down to it, other than gratifying an owners need to hold his/her new animal, what is the benefit of not waiting?
Bottom line is that some stressed snakes will tolerate being handled. Some stressed snakes will even eat. Stressed snakes will even use their hides and in general, will seem outwardly calm - none of these behaviors exclude the possibility that the animal is stressed.
Likewise an acclimated animal can strike, go off feed or act agitated.
When I move a snake from one enclosure to another, I give it time to adjust to it's new surroundings. When I get a new snake I give it time to acclimate.
I'm not saying that everyone should wait seven days. I'm just advocating that it's a relatively painless way to INSURE that there are no issues acclimating new arrivals.