This achievement is actaully missable. You will have at least 3 opportunities to get this achievement during the WSR, but it is advised that you get it as soon as possible.
You'll get your first chance during Season 2, and another two chances during Season 4 (Z06/Viper & Atom/X BOW R). Just make sure you keep an eye out on the vehicle challenges during these seasons and change the difficulty to "Very Easy" before doing doing anything on this track. The target times are quite lenient and I was personally able to fulfil the requirements of this achievement 3 times during the WSR on normal difficulty. If you are about to pass the finish line, and you don't think you'll make the 5 second cutoff, make sure to pause and restart it. Also, make the most use out of your flashbacks.