class Options
    {
        [Option("startDate", Required = true, HelpText = "The start of the date range. yyyy-mm-dd")]
        public DateTime StartDate { get; set; }

        [Option("endDate", Required = true, HelpText = "The end of the date range. yyyy-mm-dd")]
        public DateTime EndDate { get; set; }

        [Usage(ApplicationAlias = "myExe")]
        public static IEnumerable<Example> Examples
        {
            get
            {
                var dateA = DateTime.Now.AddDays(-7);
                var dateB = DateTime.Now;
                yield return new Example("Normal scenario", new Options { StartDate = dateA, EndDate = dateB });
            }
        }
     }

Normal scenario:
myExe --endDate 3/20/2018 11:46:56 AM --startDate 3/13/2018 11:46:56 AM