Poller.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace ConsoleApp1
{
    class Poller
    {
        private Timer _timer;
        public event EventHandler Tick;
        public event Func<object, EventArgs, Task> OnPollEvent;

        public Poller()
        {
            _timer = new Timer(TimerTick, null, 3000, Timeout.Infinite);

        }

        private async void TimerTick(object state)
        {
            if (OnPollEvent != null)
            {
                await OnPollEvent.Invoke(this, EventArgs.Empty);
                Console.WriteLine("Poll wait (3 secs)");
            }

            _timer.Change(3000, Timeout.Infinite);
        }

    }
}

Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {

            var timer = new Poller();
            timer.OnPollEvent += Update;

            Console.ReadKey();

        }

        private async static Task Update(object sender, EventArgs args)
        {
            Console.WriteLine("Waiting for 10 secs.");
            await Task.Delay(10000);
        }


    }
}