Technically, this achievement is missable, but you can work towards unlocking it from the very beginning of the DLC. As soon as you start you will encounter the first group of goons. make sure to hit each one with your shield by double-tapping
.
This should net you 3 hit goons. Go into the next room and hit two more goons and the achievement is yours.
You can also start working on the other "hit 5 goons with gadgets" achievements from the very beginning.
(video credit: Trophy Germany)
Hope this helps you guys!
Any improvements? Please let me know in the comments below!