Early in war, to wait until units are "100% preparation" will take time and may throw off the timetable for conquest.
ANY preparation will likely be picked up by Allied Intel and they will be warned and will have time to prepare.
As for the first part of this statement, any prep is better than none. So, right you don't have to wait for 100%, you don't have that luxury.
As to your prep being picked up by 'Allied Intel', who cares. Its not like he doesn't know that I'm going to attack Hong Kong, Palembang, Singers, or a plethora of other sites early in the game.
Later in the game is another story, but then again how many late war invasions is Japan going to make. OTOH there is a chance for subterfuge here. Prep for and don't invade. I do it all the time, even playing the AI just to get in the habit.


