First of all, you don't know how you will feel at 50. Old age has its own rewards.
When my older kids were small I thought I'd do myself in when the youngest turned 18. I had another baby when she was 13, so that plan went out the window. Then I started having grandkids and wanted to stick around to enjoy them. Also along the way I had a few health issues which I might have died from if not treated. I found that I very much did not want to die.
Now at 60, I sometimes feel that the best is past and there is nothing to look forward to, but I also know that you never know what tomorrow will bring. I am now in a good situation that I never dreamed would come my way.
I think your thinking and priorities will change through the years. Heck at 50 you're a half a century old! Something to be proud of! It's not all downhill after 50.
So to answer your question, you can set a date but I'd bet when the time comes you might feel differently.