To unlock the Before trophy in Far Cry New Dawn, you will need to find collect all of the Dear Photographs in Hope County.
To start collecting the Dear Photographs, you will have to pick up the photograph from the second floor of Prosperity, which will unlock the A Thousand Words quest to collect the remaining nine photographs.
Please note, you can only collect all of the photographs after you meet Joseph Seed in Act 2.
You can find a video showing all of the Dear Photograph locations below (credit to xTGE on YouTube for the vide):