Firstly, you should not be putting your 8 month old baby and 8 week old puppy on the floor together. Secondly, you definitely should not be walking away from that situation. Your pup is going to do what 8 week old pups do. They investigate things with their teeth. If they were with their littermates they would be practicing playbiting and wrestling with them. That is just what she is going to do, so you have to manage the situation.
When the baby is on the floor, the pup should be busy in the crate with a chew toy. When the pup is out, the baby is in a high chair or play pen. Baby gates are great tools to keep them apart. Keep the pup tethered to a door knob and busy with a puzzle toy, or tethered to yourself so you can keep an eye on her at all times. Large exercise pens allow the pup to be in the same area as the family with plenty of room to play and move, but the security of knowing that if you have to leave the room to answer the phone that both baby and pup are safe from each other.
Puppies are unpredictable. Babies are unpredictable. Don't set them up for an accident. Start teaching you pup the "leave it" cue now. Search this site for articles and threads on how. This is a valuable behavior to have on cue and you'll be able to use it on anything--toys, the baby himself, dropped pacifiers, poopy diapers--everything that babies have or do that you wouldn't want your puppy getting into. Make sure the pup is only allowed to interact with the baby on your invite.
Keep the pup's toys in one area. Relocate the pup to his bed or mat with his toy. Fill the stuffable toys and tether your pup at his mat with the toy to keep him busy. If you do it consistently, the pup will learn to bring his toys to that one area which will help keep them away from the baby.
Don't forget to teach your baby the same respect for puppy that you expect the pup to have for him. Nothing pains me more than to hear someone say that their dog "lets the kids drive their toy trucks all over them and doesn't do anything." Even if a dog would tolerate that, they shouldn't have to put up with it.