I also have a 4mo. old and he will eat anything and he especially loves paper for some reason. We live in a small apartment so it's hard sometimes to keep stuff of the floor because we're running out of space to put stuff. But...things like wires, even some furniture, basically whatever you dont want chewed on..spray with a bitter spray. You can get it just about anywhere. I got mine at Petsmart and its EXCELLENT! I accidently got some on my finger and didn't know it and touched my mouth...it tasted awful! Chewie wont even go near stuff I've sprayed. This is the brand: by Pet Botanics: Indoor Bitter End "The Trainers Friend". Here's the link to what the bottle looks like on Petsmart.
Bitter End Pet Repellent - Training & Behavior - PetSmart
Ignore the 1 star rating by the one customer. Somehow his dog actualy liked the taste of the spray, but honestly I don't see how anything would like its taste...it's an extremely bitter metallic blah taste but completely safe for the dog...LOL... Good luck!