When someone suffers a debilitating injury or has lived with a disability that prevents them from living their lives in the way they want, it is abundantly clear to those individuals when their issues "began." Proving that is irrelevant in this context: they know, on a deep and personal level, how their lives have been impacted as a result of an injury or disability.
Where proving this fact does become relevant is when the Social Security Administration becomes involved. When you are seeking Social Security Disability Insurance (SSDI benefits), you have to prove what is called a "disability onset date." Your disability onset date is the moment in time when you became unable to work as a result of a disabling medical condition.
Unfortunately, what this date means is that if the Social Security Administration awards you SSDI benefits, you will not receive retroactive payments for anytime before your disability onset date. This date can also drastically affect your pay period for benefits, or even your eligibility for benefits. The disability onset date is an incredibly important part of the application process, and you have to be prepared for it.
Providing a wealth of information to the Social Security Administration is critical in this regard. Your medical history and records, as well as your work history are important. You should also give them sufficient evidence about your medical condition, as well as any allegations and testimony you can provide that supplement your claims.
Source: FindLaw, "What is My Disability Onset Date?," Accessed Sept. 1, 2017