If they approve you for Disability it begins on the date that you filed the first initial pile of paperwork.

They don't look back at your history and say " Oh you were disabled at that age or that date"

They need any medical records you have to help them determine if you do in fact qualify for disability. They will also send you to there own Doctors for an evaluation.

It can be a complicated process to be honest. Just fill out the paper as best you can.