Here are some items that you may want to buy ahead of time while you are waiting for your new puppy to come home to you!
Crate: We strongly recommend crate training your puppy. Dogs are "den animals" and actually prefer the security of a crate. It is also invaluable for housebreaking. A 24" crate is more than adequate for one puppy and will work for the entire life of the dog. A 30" crate works for two pups, again for their entire lives. We recommend the plastic-walled crates, as these are best suited for travel. There are wire cages and soft-sided crates that are easily collapsible, but the latter can't be used until your puppy is a bit older and used to a crate. These can be lined with pieces of an old blanket or towels or the little fleece beds at Petco, PetSmart, etc. are great, too.
Dishes: Stainless Steel is the way to go. They are very easy to clean and wash up nicely in the dishwasher. Plus, they are not porous and cannot harbor bacteria.
Food: We feed our puppies and dogs Life's Abundance Food, small breed puppy. We use the puppy food until a year of age or so. The regular Life's Abundance is great from then on. Neutered or spayed dogs do very well with the weight control option, but if your dog is very active, then the regular is fine. It is most important to keep your dog on the lean side ...overweight Cavaliers are much more prone to mitral valve disease of the heart.
Treats: Our favorite treat for our dogs are plain, unsweetened spoon-size shredded wheat. Baby carrots and plain Cheerios are great, too. Be careful with rawhides. They are a BIG choking hazard and should only be allowed under supervision; also make sure it is made in the USA! Cheerios are great for training, especially housebreaking. Reward your puppy outside immediately with a Cheerio after its "business" is done.
Collar and Leash: For a puppy, choose an adjustable collar, 8" - 12" in length and 1/2" wide. Lupine is a great brand, as they have a lifetime guarantee, even if it's chewed! Many collars have available matching leashes for the ultimate in cuteness.
Grooming: Frequent grooming is a must for your Cavalier to prevent tangling and matting. Starting early with your puppy with gentle brushing will accustom it to the feel of the brush. Most Cavaliers LOVE to be brushed. Use a WIRE comb or brush for the ears. There are combs with rotating teeth, which will not pull the hair. A regular bristle brush works great for the rest of the body.
Toys: All puppies need to chew. The wider variety of toys that you provide will lessen the chance of shoes, books, furniture being chewed. This chewing need persists into adult life. Nylabones are great! They come in varying degrees of hardness. The puppy level is soft and rubbery and the adult ones are harder. We use the ones for our adults, designated for "powerful chewers". Kongs are also a good toy, again in puppy and adult versions, including smaller sizes, perfect for your grown Cavalier. Kongs can be stuffed with peanut butter or the Kong Cheese; putting yogurt inside, then freezing is also a great treat. Kongs will keep your pet very busy. Stuffed toys or soft rubber toys are fun, too. Best to remove the squeaker to prevent choking. Any other toys that strike your fancy are fair game!
Cavalier King Charles Spaniel, A Comprehensive Guide to Owning and Caring for Your Dog
by Juliette Cunliffe from Kennel Club Books - 2004
An Owner's Guide to a Happy Healthy Pet: The Cavalier King Charles Spaniel
by Norma Moffat from Howell Book House - 2000
These books should be readily available at Petco, PetSmart, Chow Hound, etc.