Attaching timer to a piece of javascript

How would I be able to attach this timer to the javascript?

The numbers should only appear on the screen when the javascript gets loaded.

Timer Code
https://jsfiddle.net/ep0q48n7/

Code I want to add it to.
https://jsfiddle.net/tswezh6u/

(function manageCurtain() {
  "use strict";

  function hide(el) {
    el.classList.add("hide");
  }

  function coverClickHandler(evt) {
    const cover = evt.currentTarget;
    hide(cover);
    const curtain = document.querySelector(".curtain");
    curtain.classList.add("slide");
  }

  const cover = document.querySelector(".jacket");
  cover.addEventListener("click", coverClickHandler);
}());

const videoPlayer = (function makeVideoPlayer() {
  "use strict";

  function onPlayerReady(event) {
    const player = event.target;
    player.setVolume(100); // percent
  }
  let hasShuffled = false;

  function onPlayerStateChange(event) {
    const player = event.target;
    const shufflePlaylist = true;

    if (!hasShuffled) {
      player.setShuffle(shufflePlaylist);
      player.playVideoAt(0);
      hasShuffled = true;
    }
  }

  function addVideo(video) {

    const playlist = "M7lc1UVf-VE";

    new YT.Player(video, {

      width: 640,
      height: 360,
      host: "https://www.youtube-nocookie.com",
      playerVars: {
        autoplay: 0,
        controls: 1,
        loop: 1,
        rel: 0,
        iv_load_policy: 3,
        cc_load_policy: 0,
        fs: 0,
        disablekb: 1,
        playlist
      },
      events: {
        "onReady": onPlayerReady,
        "onStateChange": onPlayerStateChange
      }
    });
  }

  function init(opts) {
    load.js("https://www.youtube.com/player_api").then(function() {
      YT.ready(function() {
        addVideo(opts.video);
      });
    });
  }
  return {
    init
  };
}());

(function iife() {
  "use strict";

  function show(el) {
    el.classList.remove("hide");
  }
  
  function initPlayer(wrapper) {
    videoPlayer.init({
      video: wrapper.querySelector(".video")
    });
  }

  function coverClickHandler(evt) {
    const wrapper = evt.currentTarget.parentElement;
    show(wrapper);
    initPlayer(wrapper);
  }

  const cover = document.querySelector(".jacket");
  cover.addEventListener("click", coverClickHandler);
}());