Minimum Age for Chin Augmentation?

If you want a sliding genioplasty instead of a Chin Implant, you should find a board-certified, experienced surgeon with many favorable photos.
You may want to research the risks and benefits of Chin Implant Surgery. Silastic implants are FDA approved, and have a long track record of safety, and predictability with only a week of downtime.
I hope this is helpful for you.

For males, the appropriate age for a sliding genioplasty would be 18 in my opinion. This is due to continued growth of the mandible in proportion with the rest of the face. You might also consider a chin implant which would not mess with the underlying bony structure as an another option.