When to mention in a post about a substantial edit?

Question

I have recently made substantial updates to both an answer and a question. This involved adding notable qualifications to an answer, and added notable clarification and concerns in the question. It also involved edits throughout the post, not just something I could tack on at the end.

The question is: at what point and how should I mention a substantial edit in an answer or a question?

Is a note at the top of either Q or A saying "Edit: 09/xx/18 Added blah blah" for the important changes a good idea? I've seen several posts with edits at the bottom when added clarification or questions that come from the comments, but what about when a "tack-on" edit isn't so easy?

I recently just (5 seconds ago) learned that anyone can see the edit history of a question, but that doesn't make it obvious to someone who previously sees a Q or A and assumes nothing new is there without a note. With regards to "at what point" a note would be appreciated, a "substantial" edit is enough definition for me, or one that "noticeably" modifies the effective answer or question, but I bet that someone with years more of experience than me may have a better, more specific, or different answer. I didn't find any very related questions on this.

Answer 1

As you've discovered, whenever a question or answer is edited, there's a clickable timestamp showing the most recent edit. Although it's true that on lengthy posts like your examples, the "Edited" link is somewhat hidden at the bottom, it's still quite visible to anyone who looks at the whole post.

Also, you might not have noticed that when someone other than the original author edits, their avatar is shown on the "Edited" link which makes it very visible. For example, this question has clearly been edited:

What does it mean that "the two natures of Christ cannot be separated"?