When the quote loads, you should start typing straightaway. In my experience with KeyHero, if you don't start typing the quote immediately or wait a minute before starting it will affect your speed considerably. The longer you take to start typing, the lower your wpm will be.
Best to quickly begin typing, you can press escape when in the middle of the quote and KeyHero will load a new one.

If you do not finish a quote and either hit escape or click start for a new quote your overall WPM is not at all affected. If you hesitate and then finish the quote after a time of sitting there your WPM is affected. If you stop a quote the stats will not even be entered into your account.

I hope this helps. :)

The last sentence is the only one that is relevant to the question. And it does not even answer her question. Opting out of a quote does not affect your overall WPM in any way.

I don't believe my answer to the op's question was unhelpful, perhaps you should've read all the op's posts on the forum. Perhaps, you should Read the question properly.

If the op chose to type the quote after reading it, and it took the op a couple of minutes to decide it would affect the overall wpm of the quote typed. Obviously, if the op decided to press escape at anytime during the quote it would not count, shish! Forgive me for Not stating the obvious.

The wpm counter begins when the quote loads, Not when the typist presses the first key of a loaded quote.
Good enough for you now, afbwelter?