My problem is that I want my discordbot wait during the giveaway until the giveway is out

Here's my code :

        const Discord = require('discord.js');

        const client = new Discord.Client();

        const config = require(./config.json);

        var prefix = config.prefix;

        client.login(config.token);



    client.on('ready',() => {

        console.log('I'm online');

    })



    client.on('message', message => {



      const args = message.content.slice(prefix.length).trim().split(/ +/g);

      const command = args.shift().toLowerCase();





      if (command === 'gstart') {

        var channel = args[0].slice(2).slice(0, -1);

        var price = args[1];

        var End = args[2];

        var EndMS = End*1000;

        client.channels.get(channel).send({embed: {

            color: 3447003,

            author: {

              name: '',

              icon_url: ''

            },

            title: ,

            url: ,

            description: ,

            fields: [{

                name: 'a Giveaway just started !',

                value: 'Put'🎉' in react of this message to try to win '' + price + ''.'

          },     

        ],

        timestamp: '',

        footer: {

          icon_url: '',

          text: 'End in ' + End + ' secondes !'

        }

      }

    })

    .then(msg => {

      msg.react('🎉');

      client.channels.get(channel).send('STUFF')(EndMS); // my problem is here

    })

  }

He must wait EndMS milis and, after, choose a winner but for now, he send instantly STUFF, for choosing the winner, I will not ask it for you.
All I want is he wait before sending Stuff.

Thanks you for helping me.