Mine seems to be growing very slowly compared to my other plants (The ones that has survive my unintentional destruction anyway, lol) But looking at how much Dan's plant has grown I think maybe this is the case for this variety. I'm sure TGPS or Joyner will be able to shed some light as they are the masters of the PKN
Sorry it has taken me so long to get back to this. The PKN can be a slow starter. It has always seemed to me to be slow up until it starts side shooting. Once you see these, they start to take off pretty quick.
Here are mine that were started for this contest. They just got their first transplant today. They have just started their 2nd set of true leaves.
Untitled by GhostPepperStore.com, on Flickr