Puppy and sarcoptic mange question!!?

Hello, I've just aquired a 9 week old puppy from this horrible family that left her in a barn and locked her in a dirty basement. She came to me with horrible itching and she was going bald with sores. I took her to the vet today and they did a skin scrape for demodex (spelling??) it came back negative but she... show more Hello, I've just aquired a 9 week old puppy from this horrible family that left her in a barn and locked her in a dirty basement. She came to me with horrible itching and she was going bald with sores. I took her to the vet today and they did a skin scrape for demodex (spelling??) it came back negative but she says it's more than likely sarcoptic mange because her ears were crusty , inflammed and itchy. She was given an injection of ivomec. My question is how long after the shot will it start to work? I know her fur growing could take a while but how long till the itching is gone and she can start to heal? Thanks.
Update: Let me REPHRASE the question, I already had the vet give her a vaccine for the condition. A vaccine called Ivomec, has anyone else had experience with this drug on their pets and if so how long did it take for it to work???? I'd ask the vet but they are now closed. Keep your thoughless and rude responses to... show more Let me REPHRASE the question, I already had the vet give her a vaccine for the condition. A vaccine called Ivomec, has anyone else had experience with this drug on their pets and if so how long did it take for it to work???? I'd ask the vet but they are now closed. Keep your thoughless and rude responses to yourself. Thanks to all the other "real" answers.
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