I have had my new kitten for 3 weeks and one of my older cats is just not accepting her. I thought we were making progress last week as he would sniff her and sit and watch her without growling but now he has gone back to growling loads. It's the kind of growling I hear when he is head to head with a cat outside and it always ends in a fight. I'm worried he might attack her. They only come together when I am here for a very short period of time, the rest of the time the kitten is in a pen. Is 3 weeks still early days? Will he ever get used to her?