Last Friday I noticed that my 12 wk old pit bull was very lethargic and wouldn't eat or drink anything. ?

Saturday morning he was diagnosed with Parvo. We were sent home with an iv for fluids, antibiotics, and nausea medicine. They told us to feed him boiled chicken on Sunday, but he couldn't keep it down. Although he continued to seem a little playful, I was very worried that he might not make it. I also didn't feel like I could keep sticking an iv in the poor puppy. I tool him to the vet on Monday and he wad hospitalized. Today is Tuesday and they just called me and said that he is still playful and wagging his tail. They said he did throw up last night but since having a shot for nausea he hasn't thrown up anymore. They feel like they may be making progress so they are going to keep running the course. Should I feel hopeful? How long should it take for him to be ready to come home?