You can be surprised, but I usually sleep every night. You too? Good!
This proposal is about units movement, any unit.
AS IS
Actually we can launch a unit at any moment. We have limited way to know the ETA (Estimated Time of Arrival) of the unit, but it is easy to calculate it using distance and velocity.
Coordinated attacks are not so hard to do, all we need is have all the people doing some calculation and launch their units at the appropriate start time.
But people are spread in the game map and spread on the real world map, so some of them need to wake up in the heart of the night to launch their units.
So, actually, a coordinated attack is not the demonstration of great ability, but only say how much nerd players you have.
TO BE
I don't want to wake up in the night to launch my units.
There is also no reason to make ETA calculation hard. Having people forced to use out of game tools to do calculation is stupid, makes the game less fun, don't add any value to it.
We need the ability to set/change the time of arrival of our units. The program could delay the real start (and we could be able to cancel the order until it start) OR start immediately using an appropriate reduced speed (I like this second option more because it adds also some nice tactic effect to the game).