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I struggle with this on an ongoing basis, though less than in the past. 

First of all, I notice that experienced authors using just a couple descriptors around the time of character introduction (ideally when the viewpoint character 'thinks about' the appearance), and that's it, and the description is often less along the lines of 'blue eyes, cropped hair' (very literal) and more along the lines of 'there was a hesitancy to her gaze, or perhaps fear, which stood at odds with her formidable stance.' Le Guin describes characters along the lines of: 'all delicacy and bone,' or 'frump and fop.'

So, with those kinds of descriptions, a person can visualize the character but also something about the character's personality. Those kinds of descriptions get past some oft-proscribed descriptors too (almond eyes, chocolate skin, kinky hair, etc).

Description is a great place to immerse us a bit into viewpoint. A MC viewing a lame person as 'gimpy' is very different than one viewing that person as 'managing surprisingly well, in light of their lameness.'

Description can be extended to setting. The 'delightful crunch of snow underfoot' is different than the 'miserable endless white blanketing his dead wife's garden.' 

Description is a nice place to show the advancement of a minor character through her own arc. Vin showed this in Mistborn. Originally a street urchin most at home in rags that kept her invisible, she at first found the gowns of upper society both pretentious and bulky--but over time learned that they made her invisible in a different way, and she learned to be comfortable within them. Likewise, a character who shaves their head may be doing so for an important character-related reason.

Can you extend the description later? I'd say yes, but use the opportunity to provide movement to the character and story. Why is the character thinking about their ragged nails? It could reflect the fraught escape they had just made from the cliffs of doom (or whatever) and also present a challenge as anyone who saw those ragged nails would know something had happened. 

Answer: So, a few details up front are good, hopefully shining a light on internal character, and additional details later are fine--but will hopefully accentuate the character or story arc.