Hi, adeline!
I would say remission is as individual as the person and factors in many things so I can just speak for myself.
The last major depression I experienced was 10 years ago. Since then I've had maybe several days to a week of "minor depression" but nothing I couldn't work with. I got slammed with my second major depressive episode beginning the end of last December. I had had several major stressors throughout the year which I'm pretty sure set this one off.
Take care