conquest event deadline time to declare war

I just want to know that what is the deadline time in the ongoing conquest event to declare war. 

Means After what time left we will not be able to declare any more war.

Hi, Conquest Wars can now be declared until 12 hours before Conquest End (they will then end 20 seconds prior to the event’s end latest)

Hi Madlen, why this brief 20 seconds? Think about a tower with an upgrade completed during war, that needs confirmation after the war finishes. Now 20 seconds before the end of conquest, (a) you have to be online, (b) you need to watch the victory animation scene, and © confirm the tower upgrade. That is already challenging for one tower, but when you have more than one in that state? (Remember that you’ll have to watch all the victory animations before you can interact with the game again!) And cross your fingers that you don’t have a disconnect just then.

Why not using something like 5 or 10 minutes prior to the event’s end?