Hi,
As long as you are physically and emotionally mature and you have the support of your parents then a rhinoplasty can be an option at 16, 17 or 18.  There have been some patients who have undergone rhinoplasty even at 14 or 15 but those are very rare cases with special circumstances.  If your mom and dad are much taller than you when you are 18 then you should still wait to make sure your teenage growth spurt is complete. 

As far as the gimmicky nasal devices like the nose huggie or clips, please avoid them and save your money and avoid damaging the skin and cartilages of your nose.  They are total BS!