What you pointed out about timing is right.
When there was a disappointed behaviour or a remark by the other person got upset you, it's convenient to have a cooling time in order you to not act when your feelings are overwhelming you.

Ck2d, I go on thinking that the tone is very important. That doesn't mean everybody have to share my opinión but for me it's very important.
I don't see it condescending, I see it as a proof of respect toward the other person.

Am I perfect? Of course, I'm not. All I'm saying is easier to explain than accomplish.
I'm sure I mess it all in many ocassions.
When I was in my teens, I was talking with my best friend about how might I get on the friends she introduced me.
My friend told me something that I haven't forgotten. She said that I sometimes make remarks that hurt or weren't liked by people. Of course, I was hurt by this remark, not for the remark itself but for the content. She expressed in a careful way so I wasn't upset by her. She made me think about what was wrong with me.
Since that day, I'm very cautious when talking to people.

That criticism didn't hurt me, on the contrary, it made me think.