Just wanted to comment on this. I will start from the premise that the breeder wants to do the right thing.
It has been a standard rule of thumb, if you get a score that is getting close to not acceptable in your breed at 12 months of age, that you re x-ray again at after 2 years of age to make sure the hips have stayed in the acceptable range. However, if you get a score in a the lower numbers, meaning 10 or under and no area of high scores, then this dog is not going to have big enough changes to become dysplastic over the next year. It is possible it might get a few more points but not enough to affect the opinion on the hips.
the benefit of screening early far out weights the risk of not catching those few dogs with borderline scores that got worse (and their breeder should have retested anyway). The benefit for the breeder who has an active screening program is great and vital. They need to look at all offspring as soon as possible before breeding the parent dogs again. They (Cornell Uni) have even come up with a test that can be used at 8 months of age that is 98% accurate in the normal range if repeated at 3 years. The whole reason for developing this test was to allow screening offspring ASAP to prevent breeding more affected dogs and to allow moving forward with all the information needed.
Now if the breeder is not doing an active prevention and screening program, so they are not looking at all of their offspring hips prior to breeding the parents again, then it make no difference by increasing the age of screening anyway, does it?
Edited to add, only a handful of ANKC breeds have any restrictions on hip or elbow scoreing or breeding score directives.
Thank you shortstep,
You are right I didn't take into consideration catching the early signs by testing early. I know the rule of thumb you mention at the begining, it is a good way of doing things and perhaps is what should be looked at as an official rule rather than increasing the min age. Thankyou for your reply