My 5 year old female is due for a check-up next month that is to include stool sample. First time cat owner's question: from the litter box or do they want it fresher and without litter?
Your vet may give different instructions. Our vets say to pick out from the litter box (litter can and will likely coat it) and put in a Ziplock bag, and if the vet visit is more than two hours after the cat eliminates, to refrigerate it until you bring it. It must not be older than 24 hours, and preferably as close to the appointment as possible.
So beginning 24 hours before the appointment watch for cat defecating, and collect the poop. Refrigerate, and hope there might be another fresher "event"...