If you are leaving the military do not post-pone the surgery. My opinion is 90% of all surgeries have lingering effects. By doing the surgery now you are increasing the amount of time to discover these issues. If you are not in like new condition, go to the hospital and complain, often, if your issue has not been resolved. You might have to reapply with the FBI, but by doing things this way you will be more likely to obtain a VA disability or an increased disability. The rating might cause issues with your medical when you are hired, but it will also give you extra points toward being hired and possible place you in a higher category of veteran. As long as your medical issues do not interfere with you doing the job they can't hold it against you.
I missed out on an extra 20% by not doing this. That would take my total rating up to 40%. The rating is pretty much a guaranteed paycheck for life.
But when a long train of abuses and usurpations, pursuing invariably the same object, evinces a design to reduce them under absolute Despotism, it is their right, it is their duty, to throw off such Government, and to provide new guards for their future security.
Translation for the intellectually challenged: If the government screws the people too much, it is the right and duty of the people to revolt and form a new government.