I'd keep the kittens on the same identical diet the breeder has them on for at least a month or so. Less change is better for the young little "curtain climbers". Read about cat nutritition and make an informed decision. I've seen debates go on about canned, dry and BARF (raw) on the internet since, I got the net in 1977. I've tried them all since the early 60's and am still not sold on any specific one diet except ensuring one is making a measurable, informed decision. Understand the do's and don'ts, the necessary nutrients, the toxins and the caloric intake and you'll do fine. If your cat is living 15 years plus then at least you know you did right by them diet wise.
Back in the 60's we were not as well informed as now about diets. I had a cat that lived from 1963 to 1980 = 17 years. He beat the average by 3-5 years and this guy was a garbage disposal eating food scraps, cat food, mouse, fish you name it. He never saw a vet in his life. He was an outdoor cat and finally got hit by a car bless his soul. We are a lot more informed now and can do better by making informed decisions.
Lately, I've been trying a new game with a dry food-free feed system. I've been hiding food through out the house. I hide little bowls of dry food in various places. My two Bengal boys act like hunters and they hunt for the food. I find this really stimulates them and eliminates the bordom. I also hide Dried animal jerky and chicken claws around. They also try and keep it a secret from one other. Cats will smell each others butts to try and assess if they have a new different food source. 4000 years ago this is how cats found new food sources. I like to watch how my guys secretly stalk each other to see where the new food source is. It's a great game for them!
What ever you decide slowly change them over to the new diet over a period of 3 or 4 days.