This Seeking Tech tutorial will show you how to get the Time Paradox trophy and achievement.
For this to unlock, you need to “Create the Ocelot Time Paradox.”
This is done near the beginning of the game in the Virtuous Mission. After rescuing Sokolov, a cutscene will play where you encounter Ocelot for the first time.
After the cutscene ends, equip your knife, crouch down near Ocelot, and then attack him until he dies. The trophy and achievement should then be unlocked.
You can find a video demonstration below: