Really depends on what your going to be doing when high - if you have internal stitches then maybe jumping around at a rave would be best avoided until your healed. If you have say had a 'nose job' or a your nose restructured then you may be in some pain and again dancing about could lead to discomfort.
I do not know of any additional 'big risks' that taking MDMA two weeks after minor nasal surgery would cause.