Instinct should take over. If you stick the kittens nose on the milk or if the kitten sniffs the milk into its nose, simply suction the milk from the nose and try again. If the kitten doesn't like that teat, try another one farther up toward the mother's head. Keep trying to get the kittens to nurse until successful. This can take minutes or hours.
Kittens nursing on a queen is important to both the kittens and the queen.
The initial milk carried by the queen has important antibodies in it to help protect the kitten. Also, suckling helps the queen physically recover from the ordeal of birth. Sometimes there are problems and breeders need to recognize these problems. The very large head of a Persian is difficult to pass through the birth canal and can be life threatening to the queen because she may not be able to pass a very large kitten through the birth canal. If not, you must decide quickly after the water breaks on the first one.