
in many countries you can not score a dog till it is at least 18 months old.
If you are not in a rush, I would wait till the dog is little older than 12 months old as if she/he has not stopped growing some looseness might be there due to this. Only going by dogs that have been scored young and been little lose causing higher score and then new plates taken&scored when little older, the scores have improved due to less looseness (not in UK, as here you can only score once and 1 set of plates)