JSFiddle - React, Tailwind, and code Playground

HTML

<input  onchange="dateEntered()" type="date" name="DateName" id="fm_deliverydate" placeholder="yyyy-mm-dd"/>
<input  type="time" name="TimeName" id="fm_deliverytime" placeholder="enter date"/>

JavaScript

var date = new Date();
var dd = date.getDate();
var mm = date.getMonth()+1;
var yyyy = date.getFullYear();
var hrs = date.getHours();

if(dd<10) {
    dd='0'+dd
} 

if(mm<10) {
    mm='0'+mm
}
date = yyyy+'-'+mm+'-'+dd;

function dateEntered(){
    var userDateEntry = document.getElementById("fm_deliverydate").value;

    if (hrs >= 10 && userDateEntry == date) {
        document.getElementById('fm_deliverytime').disabled = true;
    } else {
        document.getElementById('fm_deliverytime').disabled = false;
    };
}