Seed if sown directly taken from fruit  don't need stratification  but if longer time are out of fruit then i better to stratify them in fridge  3 month.
 Young seedlings is best one or two years grow in pot and than plant outside.
 When you grow from seed kaki you will not know when tree will start to bloom and how will be quality of fruits, often from seed grown tree need more than 5 years to start  blooming first time.
 Grafted plants can start blooming sometimes in second year after planting.
 
 In this video you can see difference between  diospyros lotus and diospyros kaki grafted plants.