I brought my new 8-week-old kitten home two days ago. I separated them instantly, the kitten in my bedroom and the cat in the rest of the house. The kitten didn't take any time to adjust. He started eating, drinking, and using the litter on his own within the hour. Because he was adjusting so well I brought him out to meet my cat. They hissed and batted at each other lightly a bit but that was done quickly. Today is their second day together and my older cat is cleaning and gently playing with my kitten. There hasn't been any growling at all. I still keep the kitten in my room at night and keep them around me or my room mates when they're together, but they seem so good together. When would it be okay for them to be left alone together?