It took about 15 minutes.
https://www.ssa.gov/benefits/retirement/
Social Security offers an online retirement application that you can complete in as little as 15 minutes. It's so easy. Better yet, you can apply from the comfort of your home or office at a time most convenient for you. There's no need to drive to a local Social Security office or wait for an appointment with a Social Security representative.
In most cases, once your application is submitted electronically, you're done. Social Security will process your application and contact you by telephone or by mail if any further information is needed.
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Who can apply for retirement benefits online?
You can apply online for retirement benefits or benefits as a spouse if you:
are at least 61 years and 8 months old;
are not currently receiving benefits on your own Social Security record;
have not already applied for retirement benefits; and
want your benefits to start no more than 4 months in the future. (We cannot process your application if you apply for benefits more than 4 months in advance.)
It has been about 4-1/2 years so I don't recall the details. I was already on Medicare.