There is not latency from FOH Technically.. but there is the distance
If the FOH use a digital mixer there will always be a latency in the mixer + the distance to the Speakers and also add latency.
If FOH have Active speakeres with DSP's, or amps/system controller with DSP's there will be even more latency.
Many active speaker systems With DSP's can have up to 4-6 ms latency+ mixer maybe 1-2 ms.
On a stage you can also maybe hear echo from back wall og the venue from the FOH speakers,
if so turn up the volume in your stage monitor to hear less of the sound from the FOH.