The way you ask is too broad for Stack overflow, like what user @kevintechie said. Anyway, for sending a message at a specific time, I recommend using Cron

The possible varibles of Cron are:

Seconds: 0-59

Minutes: 0-59

Hours: 0-23

Day of Month: 1-31

Months: 0-11 (January - December)

Day of Week: 0-6 (Sunday - Saturday)

Lets say you want to send a message everyday at 6 AM, using your local time

var cron = require("cron");

client.on('message', ...); //you don't have to add anything to the message listener

let morning = new cron.CronJob('00 00 06 * * *', () => {
  // Everyday at 6 AM, it will do something you want to it to do
  let channel = yourGuild.channels.get('id');
  channel.send('Morning everyone');
});
// to start the reminder
morning.start()
// to stop the reminder
morning.stop()

Else if you want it to remind from Mon to Fri, then it would be ...new cron.CronJob('00 00 06 * * 1-5', ()=> {...