using System;

using System.Threading.Tasks;

using System.Timers;

​

public class Program

{

    private static Timer Timer { get; set; }

    public static void Main()

    {   

        var timer = new Timer();

        var action = new ElapsedEventHandler((sender, e) => {

            timer.Stop();

            CarregaVendasAtivas();          

            CarregaMesas();

            CarregaDeliverys();

            timer.Start();

        });     

        timer.Interval = 30000; //30 segundo.

        timer.Elapsed += action;    

        action(null, null);

    }   

    private static void CarregaVendasAtivas()

    {

        Console.WriteLine("CarregaVendasAtivas");

    }

    private static void CarregaMesas()

    {

        Console.WriteLine("CarregaMesas");

    }

    private static void CarregaDeliverys()

    {

        Console.WriteLine("CarregaDeliverys");

    }

}