There is no exact time, it is a gradual process. The nose is often black from birth. However, there are plenty of puppies who are born with pink noses or a pink and black spotted nose. The nose, halo, and pads (if they are to change) can start changing as early as 6 weeks. On average, the change takes place between 8 weeks and 14 weeks. In rare cases, a change can take place up as late as 6 months old. We have not seen a Maltese change from pink to solid black points after the age of 1 and 1/2 years (And this was a rare case).