I would plant the stones about 2-3 cm deep, and wait until spring: they need the cold of winter to break the dormancy of the seeds. It will probably take 7-10 years before they bear, and then don't be surprised if they are sour. Seedling trees are rarely the same quality as their named parents.

Thanks for the advice. I guess they would be okay for jam. Seven to ten years sounds like perfect timing for my daughter to be making her own jam