You should apply for Social Security disability benefits (SSDI and SSI) as soon as you are eligible. If you have a disability and are either (1) unable to work or (2) no longer able to work full time, you should file an application for disability with the Social Security Administration.
You are eligible to file an application for social security disability or SSI either (a) the day after you stop working, or (b) the day after your earnings fall below $1,100.00 per month.
If you are disabled and fall within one of the two options above, you should contact your local social security office and begin the application process.
Please note that neither of the two options above allow for you to apply while working full time. Many prospective clients call me and state they want to apply for disability while working full time so they can have the disability benefits in place before they quit their job. Unfortunately, it is virtually impossible to apply for disability in this order.
If you are working full time while applying for disability, you will be immediately denied under step one of the five step sequential disability evaluation process. For this reason, you must wait until you stop working, or until your income drops below $1,100 per month.