How to unlock: Collect and uses Chronon Sources to upgrade either Time Stop or Time Dodge three times. Each one requires 11 Chronon Sources to fully upgrade.
Earliest opportunity to unlock the achievement: Act 2, Part 2. Just after Jack inspects Will's briefcase and exits the other door of the trailer, he finds the 11th Chronon Source in the game. Assuming that the ten previous Chronon Sources were picked up, he can use the 11 Chronon Sources to upgrade either Time Stop or Time Dodge to it fullest potential.
When you pick up a Chronon Source, you are prompted to upgrade by pressing the View button. You can then select the ability you want to upgrade and hold down

until the upgrade registers. If you want to upgrade at another time, after pressing the View button, press

for the upgrade screen. Then select the ability you want to upgrade and hold down

until the upgrade registers.:
Time Stop: 1 Chronon Source -->Increased Strength, 4 Chronon Sources -->Increased Size, 6 Chronon Sources -->Extra Activation.
Time Dodge: 1 Chronon Source -->Increased Focus, 4 Chronon Sources -->Maximum Focus, 6 Chronon Sources -->Extra Activation.
There is no rush to unlock this achievement and you may prefer to upgrade other abilities instead of concentrating exclusively on either Time Stop or Time Dodge for the achievement. It is important to pick up all Chronon Sources because there is an achievement to upgrade all time powers. If you use time vision frequently, it is not difficult to identify the Chronon Sources. You are further aided in that the Time Vision Icon on the right side of the screen flashes when you are close to a Chronon source.