Immediately...always a good idea to have it Write it on your supermarket list and buy it Even before you get your Newfoundland WHY? Fleas & TICKS carry diseases that itch and can be transmitted to humans. Protection even against mosquitoes too. Yes,one of the first lessons a veterinarian gives you is that about worms that must be tested for and found by scooping up a tablespoon size sample of your Newf's fresh sample of stool put in a plastic bag and give it to your vet for study under microscope. This should be done according to your Newfs requirements that your vet will advise.,... AnnaPenrod 😎 Medications will be prescribed.