This is not a hard fast rule, but is something to be aware of when picking pups. I've used as an example a pup from my last Shikoku litter. We'll see how she turns out, but she does worry me just a bit since at 2 months she already looks 'finished'. A pup should have room to grow into, something we describe as 'nobi' (length).
Anyway, that was just a random thought I had as I looked at these pictures of Kaori. The good news is she's close by so we'll all get to see how this experiment works out.