So my cat is 2.5 years old right now and I'm currently thinking of getting her a new friend. Would it be better if adopted a kitten 3 months or 6 months compared to say 1 years+? My cat is pretty skittish but does hiss and growl at other cats around so I'd like to give my cat the best chance she's got. I know about the slow introduction but not sure if the new cat's age matters or not.