Is blepharoplasty ever recommended for a 19 yr old?

Blepharoplasty. age is not the defining factor in choosing blepharoplasty. Have your eyes evaluated by a board certified surgeon with expertise in eyelid surgery.
Occasionally. Yes and sometimes it is even performed on younger individuals for congenital eye disorders such as blepharoptosis or lag ophthalmos ("droopy eyelid) in which the vision is obstructed.
Not usually. It is usually recommended when there is excess skin in the upper eyelids or bags under the eyes.
Yes. Blepharoplasty under 19 years old can be performed for many reasons; heavy or drooping eyelid, asymetrical eyelids, baggy lower lids and even puffy upper lids interfering with vision and often to create double fold in asian eyes.
Yes. Blepharoplasty at a young age (even 19) is common amongst some asians seeking to create a "double eyelid" fold. Otherwise, and in my experience it is a procedure only rarely performed (and on the lower eyelids only) on young people who have inherited bags beneath their eyes (very often in girls from their father). If prominent, these bags never disappear and only worsen with age.