It is very simple. Just play a level of the ranking mode and build your way to one of the Time Bonus boxes. But be careful! The way to these boxes has to take less than around 12 seconds. The Time Bonus gives you 15 seconds, but the restart of the level takes a few seconds as well. You just have to repeat that road to get some seconds per process. But keep in mind: when you decide to do the level to complete it, and this is something really important now: you must have more than 175 seconds left. So...to be very safe while trying to get this achievement. Just build up a wall of time that will not break very soon.

I did it within the first level: This is just the path to the Time Bonus I used...I think I got around 5 seconds per run.