Record future plans

[JohannesFKnauf]

Sometimes you already know about a future event (vacation, holidays, planned appointments, ...). You want to already record it in your timeline, so you won't forget it later.

At the same time, you don't want to record it as final. Reality may turn out differently than your plan.

Hence, I'd like to have a feature to record a planned event up-front and confirm it once it really happened (or adjust it, if it happened in a different way than my original plan -- e.g. a meeting took 15m longer).