Like I said before that is not what the plans in HOI IV do, in HOI IV everything is ready but the units need to remain idle
Incorrect. You draw up the plan, assign the units, and then the units move to the required position for the plan.
Maybe they are sending every soldier on tour to the target area during the night or on a mosquito to make sure they are physically fit and won´t get lost on their way to the target?
Or, more reasonably, they are ensuring that the supply chains are arranged, coordination with air and fire support is in order, various unit and sub-unit commanders are briefed, specialist personnel are in place, and all the other many, many things that a formation is supposed to do before the plan it is apart reaches the execution phase. You are ludicrously underestimating just how much preparation goes into a major offensive in modern war, even at the sub-divisional level.