"Untimely passing" is probably more common. Someone who dies "too soon" usually from some illness or accident.
Doesn't it mean a insult or nagging? because if you tell some has died at good timing then it means that he doesn't deserve to live more or something like that.
Haven't you ever experienced a person who has lived a good long life and their death seemed appropriate?
I can't say I have ever seen "timely passing" no matter how long and full the life of the person has been.
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