We recommend waiting until your dog is at least over 6 months and likely even older for larger dogs. The benefits are much more pronounced in larger dogs.
The general recommendation is to cut approx 2mm away from the quick. But if a dog has black or dark claws it can be difficult or impossible to see the quick.
Puppies should begin eating solid food about 3.5 to 4.5 weeks of age. Initially, make gruel by mixing a milk replacer with a small amount of puppy food soaked.