How Long To Keep New Kitten Isolated?

I have a 9 week old kitten, she is very sweet and friendly. I think the only problem is that my boyfriend is allergic to cats so I am not 100% sure if she has fleas or any other pest problems yet. She is being kept away from him for now but it might be time to introduce her to him soon? My question here would be how long do you keep your kitten isolated with your partner before introducing them?? A few months maybe even a year??