Shaving Nose Hump in a Short Time Possible?

I would agree with your surgeon.  Although it is best to wait 6 months to one year after your initial surgery, this is not the case here.  There is a specific abnormality that he feels he can correct with a minimally invasive touch up.  I think you should proceed.

Most surgeons feel comfortable performing same site surgery after a year. Sometimes this can be shortened to 6-8 months. For example if a Septoplasty was initially done, then it would be possible to safely perform a rhinoplasty 6 months later. Although both are located in the nose, there involve different tissues. The reason is to allow the surgerized area to heal and the inflammatory reaction to die down. Revision surgery is hard enough not to have further compounding issues to deal with.

If a dorsal hump persists after nasal surgery (and if that is the only residual deformity), then it is very straightforward to simply shave down the remaining bone. This can usually be accomplished through incisions on the inside of the nose. The amout of swelling and bruising is usually very limited,and the "down-time" afterwards is minimal.