Once the dog or puppy has been dewormed the deworming medicine will basically Paralyze the worms in your dogs intestines and then the worms will begin to detach from your dogs intestines.
Once that happens the dog or puppy should begin to poop out the worms within one to two hours but for some dogs it can take up to 12 hours before the dog will begin pooping worms and the dog could continue to poop out worms for up to two weeks after being dewormed.
It's also a good idea to keep your dog dewormed by getting them the medicine as often as the Vet tells you too to prevent your dog from getting worms in the first place.