This is an unmissable achievement.
During the storyline after some some fighting you will see a cut scene involving the Talon Leader and some Cerberus troops, after a short talk with him/her you'll take control of your character again. The achievement will pop then when you have control.
There isn't much else I can say about the achievement, it's the first achievement you'll have the chance to get and that it is story related.
I'mt trying to keep spoilers out and useful info in so sorry if I can't tell you more.