I would agree with guys if dog is willing to work let him as some dogs mature early and have a head for work I had a pup that was keen to chase work at 7 months and I was tempted to hold her back but I gave small bolts when ferreting twice a week by the time pup was 18 months it was a machine and to be honest best dog I have ever owned sometime just trust nature and give pup it's head but I wouldn't let it work more than twice a week keeps them keen just my opion but ken lots disagree we this approach