How can I help my 5 1/2 week puppy socialize and have a good biting inhibition.?

I adopted a 5 1/2 weeks old puppy from a non reputable breeder (my bad) I already put a deposit on her and was told by the breeder that I can take her home at 6 weeks so I did my research and found out that you should only bring puppies home at 8 weeks. I contacted the breeder and asked her if she can wait 2 more weeks but she said the vet already released the puppy I asked her what food the puppy is eating and she said cesar puppy. at 5 1/2 weeks the breeder texted me and said I can bring the puppy home already and all her litter mates are gone and they took the mother away from her so I felt like the puppy will be better of with me as she feeds her none nutritional food and I was afraid she would not take care of the puppy. I can't turn my back away from the cute puppy as I know she needs me more now. My questions is how can I help her be more socialize to other pets and how can I teach her good biting inhibition? would day care works for her or puppy class? I can take her to a puppy class on her 7th weeks or day care at 9 weeks what can you all suggest I can do to help her. I really feel bad that I got her at her early age this is the first time I'm owning a pet and I thought I did my research already but apparently it's not enough but there is nothing I can do know except to help her. Thank you

Try to play with your puppy, let him mouth on your hands. Continue play until he bites especially hard. When he does, immediately give a high-pitched yelp, as if you’re hurt, and let your hand go limp. This should startle your puppy and cause him to stop mouthing you, at least momentarily.