When is good time to end one's life?

I have seen up close and personal the anxiety and marginalization of the aged, its disturbing. Loss of control of ones fate, one’s body and mind and at the mercy of others care. Some time well intentioned, but most of the time; no matter how well intentioned its a matter of warehousing. Just the facts——please no altrustic responses, would just like nuts and bolts responses on how and when to check out. God willing i have about 20 yrs left and I’d like to be prepared.