To unlock the Timed to Perfection trophy in FIFA 19, you will need to score a goal using the new timed shots feature that has been added to this year's iteration of the series.
To do a timed shot, you will need to press the shoot button and then press the shoot button again at the perfect moment. If you have the Trainer overlay turned on during matches, you'll see a meter appear above a player's head when you are shooting.
You will need to press the shoot button a second time when the timing meter is in the green section and score for the trophy to unlock.
If you're having issues timing and scoring the shot, you can adjust the gameplay settings to make it easier, play on beginner difficulty, and play with a 5-star team against a 1-star team.