A COMPLETE guide of all 200+ collectibles with timelinks can be found HERE
The collectibles, including 60 chronon sources required for upgrading time powers, are found within Act 2 through to Act 5. They are found using the time vision ability near them to reveal and collect them.
Upon picking up the last chronon source, you will can buy the last upgrade and be rewarded with the achievement.
You can replay chapters using the timeline at any point, but keep in mind that changing your choices within the Junctions will add new collectibles for you to collect, bringing your percentage down. You can quit to the main menu once you collect them and reach a checkpoint save.
Lastly, use the menu to check "Collectibles" & "Upgrades" where it'll show your collectibles for each Act/Part so you can easily keep progress.
Alternatively, please see this video which is the beginning to the collectibles guide video playlist:
Upon finding all collectibles, you will have the following achievements:
The Media Baron achievement in Quantum Break worth 49 pointsYou need to find all Emails, presentations, TV Shows, Radios And Posters