It is important to train your kitten at a young age to use the litter box vs when they get older because the older the cat is the less likely it is to change its patterns that it has been using its whole life. When it comes to younger cats it is easier to train them to go to the bathroom in a litter box because they don’t have a set way yet and they are still learning different life skills. It also helps that their brains are also still developing which helps with picking up new skills and learning them quicker.