I think my puppy has parvo?

We bought a 8 wk old Chihuahua puppy from breeder on Saturday 7/12. He acted fine he was playfull and ate well. As a precaution I took him to my vet on Monday morning 7/14. She did a well puppy checkup and said everything appearded to be fine. Around 4:30 pm the same day he threw-up after he ate. So I gave him some nutrical and he trhew-up again. After this he refused his food and would only drink small amounts of water. Around noon the nest day 7/15 he began to have very runny poop tan and yellowish in color. I calld the vet and she wanted to see him a 4pm. I took him to the vet and she took one look at him and said that he need to stay she would give him IV fluids and meds to stop him from throwing-up. She would not confirm or deny parvo until she did a parvo test. I should know something soon. I know we just got him but we are already attached to him. What are his chances of survival if it is parvo? How long once exposed to show signs? He only had 1st shots 7/10.