With hounds I had 9 months and my Abel dog ( BMC ) started to really show bottom at about 13 months and has got better with age. I think the line and type/breed would effect that a lot myself
x2, it depends on the strain and breed. The mtn curs I used to keep usually were hunting good with the pack by 10 months old and some struck on there own at that age and would stick pretty good. Some would drop out at 10 months old after 15 minutes but I gave those a few months like until 13 or 14 months. I would remember this so that It didn't matter how good they were after that...they did not get to breed. I always made sure it was the early starters that were the breeders.
At 1.5 years of age they better be striking and sticking or they do not stay.