It increases the flash effect (ON -> OFF) so the show looks more intense.
I'd suggest you to play a song that has a big drop between a calm and an intense section. Then, just note how long the lights take to reflect the very first beat of the intense section, this will be the value to set in the Time Offset option.
For my own tests, I use the song "Down" by the artist "Metr" between 0:50 - 1:25.