spitz puppy nose colour...

this is my first thread, im about to get a japanese spitz puppy and at the time i didnt think anything about it but i have realised that the nose is not yet completely black, makes me a little worried as 1 puppy has a full black nose and the other 2 are very spotty pink and black. they claim that they are pure and one is registered but the other isnt but his parents were,
will his nose turn all black before i get him? hes only 3 weeks old, will be getting him at 8-9 weeks.