Arduino effect to enable leds for 5 seconds when white flag is raised

Hi, I've successfully configured SimHub to connect to an Arduino that has a bunch of WS2812b leds. I already added effects for left/right car, yellow flag ... it works great!

But I'm struggling to add an effect for the following scenario: when the white flag is raised, I want to flash/enable some LEDs for 5 seconds, and then turn them off. I believe the "white flag on" effect, will enable the LEDS for the entire last lap. But I only want to enable them briefly when the last lap begins.

Any ideas?

Thanks!