I didn't have a buffer when I stopped working. I refer to it as "stopped working" and not "retired" because, at the time my company went out of business and laid me off, I spent a year or two considering the possibility of going back to work at some point.
My numbers were marginal at first, so I was entertaining the possibility of some kind of work in the future, if things didn't work out. Then 2 things happened. I came into a modest sum from my father's estate, on his passing. This, combined with what turned out to be the most marvelous bull run, graduallly eased me into retirement.
In my case, my "buffer" was my flexibility, and ability to turn on a dime. I am single, with no kids, so these sorts of lifestyle and economic decisions are much easier for me than some others.