First of all, plastic surgery is not a disability compensation project, without affecting the function and disfigurement, just for good looks. So it doesn't make much difference whether to do the identification now or wait until after the operation, because you need to bear the expenses yourself.
Secondly, if the operation is not for treatment, it can be done or not. If there are economic conditions, you can do it or not.
Thirdly, if the appraisal is favorable, you can get the compensation earlier now, and you will get the compensation later after the operation.
I hope I can help you!