Yup. The stretch should go for another couple of weeks then watch as those little hairy budlets fill out in earnest.... Are they looking okay ? ...
Tbh you are right picture don't really tell the tale but they are mostly dark green I will take better pictures when lights onWith the yellow hue of the HPS lights, it's difficult to see if you have any deficiencies.
Now - I am a soil dude so I won't try to provide advice on nutes for your medium. But fear not - if I know this RIU community, a coco grower will be along shortly.