The documentation for the MP3 Trigger states for the #RAND function:
The default behavior of the random trigger function is to play a random
track from all the MP3 files on the flash card. The #RAND function will
exclude the first N tracks (in the directory) from the random trigger
function. So if there are 18 MP3 files on the card and N=4, then the
first 4 MP3 files will be excluded from the random trigger function.
Therefore, if you want to exclude the first track, the init command should be:
#RAND 1
Now, as TS-Chris mentions, the MP3 Trigger unfortunately uses the order of the directory entry rather than the track name numbers to index tracks for the Random, Next, Previous functions. So to make sure that things are in the correct order, you should copy the tracks incrementally to a newly formatted microSD card. The WAV Trigger and Tsunami use the actual track numbers for everything and are much easier to work with in this regard.