You've still got PLENTY of time before you start to worry! I know how it feels to have your baby hissing mad though.

When I first got Shiloh, I had my Lab and the two of them became the best of friends. Dessi died after a couple months and then Shiloh was the only pet. One day, I brought my friend's cat over to spend the night because I assumed Shiloh would love the company of another animal again. Oh boy was I wrong She spent the night tormenting the poor kitty. After that I didn't bring another cat into my house for a year or so. Then I brought in a little orange foster who I tried to introduce to her several times. She hissed, growled, spit, screamed, and carried on for hours. The foster stayed in the bathroom and I could only let him out when Shiloh was tucked into my room. She would even hiss and growl at me if I smelled like him. Then I eventually started taking in more fosters. She would still carry on with them, but once I stopped keeping them in the bathroom, I think she realized she had to deal with them. I still remember the first time she played with one of my fosters. The foster was on the kitchen chair and she was under it. They were swatting at each other in a way that was play, but also a little bit of not-so-friendly play. I was so happy that she had made progress though, I cried

Now that I've had soooo many foster cats in and out, she is so much better. She will still hiss and growl at the new ones, but she always becomes accustomed to them. She's definately in charge and keeps everyone in line, especially if I am watching. When I'm not looking though, I've caught her letting Lucky and Chance groom her and playing chase with the others. When I turn around and look, she'll pretend to get upset with the cats and turn her back. It is pretty funny

Just don't give up hope. Cats sometimes take awhile, but usually can at least learn to peacefully coexist, if not be best friends!