Should I get a rhinoplasty revision 9 months post-op?

While on the one hand, a rhinoplasty's full results are not visible for 12 months postop, the obvious changes are noticeable immediately. In regard to swelling, the tip of the nose -- the cartilaginous part -- is the last to decrease.  It is absolutely possible to assess the results of a rhinoplasty, and indeed to proceed with the revision, nine months (and sometimes less) after the initial surgery. I would continue to speak with your original surgeon who has graciously offered to revise the result free of charge. If he or she is experienced and a board certified surgeon with good reviews, I would certainly consider letting him or her perform the revision. If, however, the reviews state that many patients have not been happy with their results, I would seek a second opinion.  

Some surgeons like to wait a full 12 months prior to doing any revisions.  This is not necessary in all cases but it does ensure all swelling is completely resolved.  He probably is suggesting waiting 4 more months so a full 12 months have elapsed.  This does not reflect adversely on your surgeon.  It would probably be best to proceed with this surgeon financially since the revision would involve a cost for his services.  

A revision usually is not offered for at least a year or longer or until all the swelling subsides. Best of luck.