Here are a few points to keep in mind for Daimaju:

• Squad has to be a minimum of 4 (of course).
  
  
• Your squad has to be killed within 2 seconds of leaving the initial planning mode.
  So when that "Game Over" screen pops up the time should be exactly 00:02.
  
  
• You absolutely have, have, have, have, have to have the No Armor mod from the Workshop downloaded, or you're gonna have a hard time shorterning that death time.
  
  
  You can instead use the "no armor" option for the Shield class if you want to avoid modding.
  Thanks for the suggestion, Felipe//The Postman!
  
  
• Spread out your squad! Observe how fast each one of your troopers are dying: Are they dying the same time? Is one or two dying a half a second away from the first death?
  
  If they're not dying within a split-second of each other, that means your guys are wayyyy too concentrated. I might sound like an Holocaust officer here, but you'll need to spread out your guys for them to die efficiently.
  
  
• Reset the Doctrine just in case. These perks help to take down the enemies faster, which we don't want atm. Best to keep them temporarily disabled.
  
  
• Finally, the notification for unlocking the achievement may not appear until you've returned to the main menu or until the map is restarted.

That's all I guess.

1) Choose your map.

In this guide we'll be using one of the late-game maps: #64 Fire Station North.



2) Give your squad the necessary equipment.

Make sure to have the No Armor mod installed and equipped to each of your four troops.
It also might help if your suicide participants aren't Lieutenants, which mine were.

Might as well switch the handgun to a weaker one.

Buckled up? Yeap!

3) Planning time

Are you sure you want to continue? Of course!

Now just follow the similar paths, and avoid overlapping each other.

Then just fill up the path with distractions. This is done by right-click drags.

More!

MORE!

Now unpause and watch the fireworks.

Profit...?

For Strategist, Lone Wolf, and Quick Thinker

I was mislead that using the mission generator would contribute to the achievements. It doesn't. You instead have to get the medals from each of the official missions to unlock the achievement.
Can you see the three circles next to each mission? Some highlighted and some are not? Yea, those medals.

Some more info about the medals.
Strategist - 30 Perfect Plan Medals
Disables once you do something out of the deployment phase. Ordering the sniper to shoot (S key on default), and commencing stealth attacks (F key on default) are allowed.

Quick Thinker - 30 No Pause Medals
No pausing/planning mode after the deployment phase. You still can right click interactables such as doors and bombs, even plan your flashbang trojectory.

Lone Wolf - 30 One Man Army Medals
Clear the area using a single trooper. Pretty straight forward.


Additionally it's alot less stress-inducing if you exclude the Lone Wolf achievement and go for the Quick Thinker and Strategist as a separate package instead. You won't unlock all three achievements at once, but at least you get to avoid going through the pain of simultaneously doing no pause, single plan, and the mother-load: solo-ing all of them.


Good luck!