I think that you should give him more time to regulate himself. Watch for the signs that he shows when he has to go. Is the poop normal or loose? All three of my dogs poop 2x a day..6am and 6pm. Sometimes they do have to go in between too.
Misty- Samoyed Mix, Tannor- Golden Retriever CGC
Robyn- GSD CGC, TC, Midnite-GSD CGC,TC, Brennan-Golden Retriever CGC, Batman-Husky/Greyhound , Apollo-GSD