You don’t need to say anything – remember they have no idea what the word sit means at this point! Take a treat and hold it out to your dog’s nose, then slowly and smoothly raise your hand above and over their head. Your dog should move their head back as they follow the treat with their nose and when doing so, as their body hinges, their bottom should touch the floor.
As soon as your dog’s bottom touches the floor say “yes” and then quickly give them their well-deserved treat.