Once your DTV is issued, it’s updated in the immigration system right away. So, you won’t be able to re-enter Thailand on your Non-B and keep it active. When you arrive, immigration will see both visas — they’ll usually cancel the Non-B and give you the DTV stamp instead. Some officers may ask which visa you prefer to keep, but you can’t hold both.

My friend applied on 12th September has just got approved today, I think you maybe will get the result within this week