How to randomize between setInterval?

Question

JavaScript

Hello! There is a code like this:

const fs = require('fs');

client.on('message', function (message) {
    if (message.content !== "$loop") return;

    fs.readFile('keys.txt', { encoding: 'utf8'}, (err, data) => {
        if (err) throw err;
        const linesOfFile = data.toString().split("\n");

        setInterval(() => {
            message.channel.send(linesOfFile.shift());
        }, 10000);
    });

    fs.readFile('keys2.txt', { encoding: 'utf8' }, (err, data) => {
        if (err) throw err;
        const linesOfFile = data.toString().split("\n");

        setInterval(() => {
            message.channel.send(linesOfFile.shift());
        }, 7000);
    });
});

root - a call from the text editor of phrases that will be thrown once an hour. root2 - analogue, which should, between 13:00 and 14:00, for example, drop a number in a random interval. Something like from 13:10 to 13:50.
I can’t understand, my head no longer boils at these intervals. This is shitty code, sorry. I don’t know how otherwise .. It
’s not difficult for anyone, please help me to properly arrange all this so that it works. Now