A supplement with vitamin D should normally not be given until the growth plates are closed as the vitamin D could intensify the effect of calcium. Supplements with vitamin D include cod liver oil and unrefined sockeye salmon oil.
Unless there is a specific medical reason, my experience has been that supplements in general should be avoided until five months of age.
C and E, plus 1 tbsp safflower oil added to food as soon as we took him home at 10 weeks, per breeders instructions. no D supplements, other than in dairy products like cheese, yogurt.