People say this achievement is easy, which It can be in some instances, but I find it more luck based.
What I find quite easy which iv done a few times is to track the enemy at a distance, so that when he/she is immobilised, you can take pop shots at them and wait for them to become undetected and keep shooting at their current position. Obviously I'd recommend targeting the lower tiers as you can penetrate the front armour a lot easier!
Here are a few times where I have done it, these are just pure luck, managing to sometimes get the last shot in a second after they went undetected! Artillery are good targets too as they have very little armour.
I also done these all on the same day, you can try and go for it, but in the end you'll most probably get it while going for other achievements.