If you're only getting a fecal done, you don't need an appointment to take the snake in. Just whenever the snake goes, take the sample in. It doesn't take long to do a fecal, trust me, I've done tons. Besides, poo is poo regardless of where it comes from, so the fresher the better. If you can't get the sample to the vet right then, stick it in the fridge in a baggie or something. I've done fecals on my rats, found parasites on one of them(got her from Petco, *gag*), went to my vet, told him what she had and what I needed, and he gave it to me. No big deal. No real reason to stress the animal out by taking it to the vet for just a fecal. And who wants a fecal loop stuck up their bottom anyway?