How long will it take our male cat to get used to his kittens?

He has no idea that those r his kittens. He just sees little brats running around and messing with his female. If given the chance, he would kill the kittens, so that he can breed the female again. Getting him neutered to make sure he doesn't kill them again, and he would try to kill them even if he was neutered. Play with the kittens ALOT to tire them out, then go cuddle with daddy while the kittens are asleep.