It really doesn't matter, its a personal preference. I just feed my dog whenever he's hungry. That can be anywhere from 2 to 5 times a day.
I'd be careful with the chicken leg quarters, at 13 weeks old he still has small teeth and those leg bones are very thick even for an adult dog that isn't used to them. Personally I would not give any large bones to a pup so young, I'd be concerned about choking and damage to teeth. Yes they are just puppy teeth but that doesn't mean it won't be painful. The chicken backs are great bones to start with though. I would feed him by hand until he gets the hang of it. I think you could try some chicken wings as well once he gets a little more experienced.
I know a lot of raw feeders leave off the skin because a) its very fatty and b) it often gives the dog the runs. I never removed it because I always was trying to get my dog to gain weight, he's always skinny. But when just starting out, I probably should have removed the skin off the backs because I think it was tough to digest at first. Even without the skin, there will likely be an adjustment period ranging from loose stools and other digestive problems. Digestive enzymes are helpful to aid in that beginning, or feed yogurt.
I use to just see what he could handle on the leg bones and then cut the rest of the meat off the bone and feed it to him. I also smashed the bones with a meat hammer sometimes and it was easier for him to handle, although you have to watch for sharp bone pieces. If you cook the bones of course just make sure you remove the bones before feeding.
Article that was posted by another breeder on feeding a pup raw. id becareful with the legs quarters since the bones can be dense and too dense may cause some issues with the pups tummy. I fed Kash chix wings, but would have to use a hammer to break up the bone a little bit. If not, he would vomit up the dense part of the bones.