
Hi,
In labs it is not usual to test much before 1 year of age, there after it should be an annual test. Generally eye testing can be done from the time the puppy is 5 to 6 weeks old as soon as the eye is developed enough for an accurate test result.
Different breeds require different tests as well, each test has an ideal age at which it should be tested. This information is available from the British Veterinary Association who produce booklets on eye testing, elbow displaysia, and hip displaysia.
Polly