How run my code at specific exact time in console browser?

Hi, I want click on button at exact time, for example (11:10: 10: 122), without even a few milliseconds of error (or a maximum of 10 milliseconds)

my button 

<      document.querySelector('#btn-buy').click();       >

i wrote this code but has around(90 millisecond)error

<pre lang="Javascript"><pre>  

    var timerId;
    start = Date.now()
    execTime = new Date().setMinutes(47,59,000)

    var t=setTimeout(() => {
        count = 0
        timerId = setTimeout(() => {

            document.querySelector('#btn-buy').click();
            console.log(0);
            
        })
    }, execTime - start)

i wrote this code but has around(90 millisecond)error

<pre lang="Javascript"><pre>  

    var timerId;
    start = Date.now()
    execTime = new Date().setMinutes(47,59,000)

    var t=setTimeout(() => {
        count = 0
        timerId = setTimeout(() => {

            document.querySelector('#btn-buy').click();
            console.log(0);
            
        })
    }, execTime - start)