I have found that is a little more difficult to potty train King Charles Cavaliers, however it can be done if you are patient. I recommend that you crate train your puppy from day one!!! All of our puppies have been trained via the crate and it works wonderfully. We have a crate in the kitchen/living area and one also in the bedroom.
Once your puppy comes home, take them outside where you plan on letting them use the bathroom. Then place the puppy down and use the command that you plan on using. For example, I use, "Outside Go Potty". Once he/she goes potty praise them, good girl/boy in a slightly raised pitch and give them a treat (training treats are best as they are small). When in the home take your puppy outside every 30 minutes and repeat the same process. Tell them outside go potty, when outside keep saying go potty then repeat praise.
I use our crate in the kitchen/living are for a time for them to relax and when you are busy making dinner etc. Remember growing puppies require A LOT of sleep so keeping them safe in the crate is best for you and your new puppy. Take them to the crate and tell them "kennel", keep repeating and they will learn. When you take them out, immediately say outside go potty, etc. At bedtime, we go outside and then we take him/her to bedroom crating saying bedtime closing the doors and turning out the lights then we go to bed. Some puppies will need to go out in the middle of the night, they don't typically like to mess up their crate so they will wine/bark to go out. Say "Good girl/boy" then outside go potty then back to bedroom following the same steps as before.
Puppies will have accidents, please do not yell at them or tell them they are bad, they are babies and learning. Praise them when the do good to reinforce good behaviors. Switching treats around and using praise often makes the process go a lot easier.