For those of you who have completed the story, but completely missed the leaflet like I did, you can do the following -
Use the chapter select option at the main menu and choose '11. Unwelcome'. This will be late Tuesday. Play through the locket scene in the grassy area. After placing the items in the evidence bag in the office, you will be returned to your home. After the door has been opened, immediately look behind you and pick up the leaflet from the floor.
Now, you will have to play through the rest of the game until Saturday morning. You will be woken by the door buzzer, after dreaming Cord was sat at the end of your bed. Ignore the buzzer. Go into the living area and look at the table. You will see the leaflet you picked up and a box beside it. Focus on the box and the achievement should follow shortly afterward.