Are you trying to do clocks from games like GTA, Saints Row and etc that each hour in game is a minute in real life?
Well, you could use the Unreal vehicle example macro Timer, and do little modifications to make into a proper 12/24 hours time.
Now if you want something to happen in a specific time, like at 6pm a shower of meteor happens, I think you would have to use a Branch condition, if its 6pm, then play the animation (true), if its not, do nothing (false).