Vet Deductibles….

Hey guys! I just got a dog from the shelter and im a little confused on pet insurance. Its a lot different than human insurance it seems lol. Im aware that you have to pay the cost upfront and will be reimbursed by the insurance agency. By “upfront cost” is that the deductible??? Or is it the full price of the visit? My deductible is currently 250. My dog has his first vet visit soon. Should i be prepared to pay the whole bill or just the deductible?