Например, так:

using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;
using System.Diagnostics;

namespace ConsoleTest
{
    class Program
    {
        static void DoSomething() 
	{ 
		//...
	}

        public static void ExecuteWithDelay(Action deleg, int delay)
        {
            Stopwatch sw = new Stopwatch();
            sw.Start();
            deleg();
            if (sw.ElapsedMilliseconds < delay)
            {
                Thread.Sleep(delay - (int)sw.ElapsedMilliseconds);
            }            
        }

        static void Main(string[] args)
        {            
            ExecuteWithDelay(DoSomething, 300);   
        }
    }
}