No, I don't have an age limit because my CTB is contingent on when my Dad dies. I'm already way older than most people here seem to want to reach- I'm 43. For me- it's more like I feel there are certain things looming on the horizon that I'm simply not willing to put up with. I don't intend to put up with illness and old age alone. I don't want to go into a wage slave job again- although that looks fairly likely for the time being.
My Dad's death will be my trigger point. Not just because of the pain of it. It will feel like I have no one left at that point. But- there's also the distinct possibility a (suspected) narcissistic family member would go to the funeral. Ideally- I'd like to avoid seeing them at any cost. Seems best to try and do it asap after my Dad goes to save myself all that shit. Of course- whether I'll have the courage is another matter.
Frustrating part is- I was so sure I'd be dead by now- of natural causes. My Mum died at 40. I always felt sure I would too.
I understand where you are coming from, originally part of me wanted to possibly wait but I don't think I can last that long. And part of me wants to do it before my parents die because I don't think I'd be able to handle it (very selfish and hypocritical of me).
Also, this is just my own personal opinion (so not trying to sound mean or rude) but I always worried about staying around for a longer period of time like up to my 30s or later just because at least for me, so many things can happen in that amount of time that could make CTB almost impossible.
Like for example, what if I end of finding someone I love or to love me, or end up having kids (all of those I would never even dare to believe would be possible) but I would just fear the time leading up to if I were to wait for my parents death something would stop me. And I feel like doing it at a younger age would make it easier since I haven't seen the world yet, I have some idea of what it has to offer (mostly bad) but this way I can go without feeling like something is holding me back.
Some of me wanting to CTB at a certain age probably has to do with me telling myself I wouldn't make it past 23 but other parts of it seem to have more meaning and fear. But what I do feel strongly about is that I was never meant to live out my full life here to begin with.
I'm really happy (if that's the word you were thinking of or don't mind me using) that you have stayed this far and care enough to be there for your family until their end. You're doing something I wish I could but never will.