Random image in sladeshow but important is to be first image random and then random all images.

I using this code but first image all time is not random. Can you tell me what code can use from start to end? I use this code.

$w.onReady(function () { 
let slides = $w("#fullWidthSlides1").slides; 
let numOfSlides = slides.length; 
let indexes = slides.map((e, index) => index); 
let rnd, nextSlide = 0; 
shuffledIndexes(); 
function shuffledIndexes() { 
for (let i = indexes.length - 1; i > 0; i--) { 
rnd = Math.floor(Math.random() * (i + 1)); 
[indexes[i], indexes[rnd]] = [indexes[rnd], indexes[i]]; 
} 
} 
$w("#fullWidthSlides1").changeSlide(slides[indexes[0]]) 
.then(() => { 
$w('#fullWidthSlides1').show(); 
}) 
setInterval(() => { 
nextSlide++; 
nextSlide %= numOfSlides; 
$w("#fullWidthSlides1").changeSlide(indexes[nextSlide]); 
}, 3000) //interval in milliseconds (in this example: 3 seconds) 
}); 

The website is: https://www.dpelegal.co/ important is to be the first image random.the