Answer: first continuous, then partial
Explanation: Continous reinforcement refers to a reinforcement schedule whereby every correct response performed is praised or reinforced, here, every time John's pet correctly performs that trick, the active or response of the pet is rewarded, thus will help carry out the correct response due to the reinforcement it receives. However, after sometime the reinforcement should be partial such that the action isn't reinforced every time the trick is performed. This according to the partial reinforcement extinction effect is more erobust than continuous reimbursement.