Non-missable achievement, so long as you play the DLC.
Simply complete the "From Ashes" DLC. This will show up on the Galaxy Map as "Priority: Eden Prime" in the Exodus Cluster's Utopia system, and should become available from the first opportunity you get to set your own destination. Note that the system will be flashing, but you won't see the name of the mission displayed on it unless you scroll over it.
Once you've had a conversation with your new squadmate and the mission ends, the achievement will unlock during the loading screen as you transfer back to the Normandy.