As a general rule, it is best to forestall any nasal surgery in children until they have stopped growing. This usually means waiting till after the puberty growth spurt. As a general rule, the nose stops growing when the individual stops growing in height. Though there are exceptions, it is around 15-16 years old for girls and 17-18 years old for boys. However, even after this final growth spurt, it has been reported that there can be some further septal growth up to the age 25, which could lead to late postsurgical distortions requiring possible revision surgery. But, I think, this would be rare.
There are several reasons for delaying surgery. The most important is that surgical intervention before the nose has fully matured can affect the growth centers within the nose. This could produce an infantile or stunted nose or asymmetries of the nose. Another reason for delaying surgery would be to allow an immature face to “catch up to” or “grow into” better balance with a nose that might appear too large. Exceptions to this rule might be acute nasal trauma, septal abscess, tumors, severe airway obstruction, significant deformities, as with a cleft-lip nose or significant psychological problems.