It is almost always better to receive infomation about a result or decision before it has the chance to impact you.
There are niche cases, of course, when discovering something in the moment allows for powerful instictive reactions to take over; reactions which may be more beneficial than if you had have time to plan.
This is rare though.
Usually, finding out early is by far the best option. Which means that giving people information before it affects them is important, too. If you know someone is going to find out one way or another, why hold back?
Cut the fluff. Candid is king.