At four weeks of age kittens can be offered regular cat food. You can give them canned wet food which is easier for them to eat or you can offer them dry kitten food that is moistened with water to make it softer and therefore easier to eat.
Kittens are able to start eating real cat food at around six weeks of age, although some may need as long as eight weeks if they're slower with their development.
you can feed a kitten food at the age 8 weeks That what I have been doing. They stop feeding off the mom at 8 weeks I think its ok to start on kitten food or soft food first then you can start them on adult food with in the 6 to a year.