DateTimeElapsedEventArgs.cs

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

public class DateTimeElapsedEventArgs : EventArgs
{
    public DateTime DateTime { get; private set; }
    public DateTimeElapsedEventArgs(DateTime dateTime)
    {
        DateTime = dateTime;
    }
}

DateTimer.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Management;
using System.Timers;

public class DateTimer : IDisposable
{
    public int? Year
    {
        get { return _year; }
        set
        {
            _year = value;
            UpdateWatcherIfEnabled();
        }
    }

    public int? Month
    {
        get { return _month; }
        set
        {
            _month = value;
            UpdateWatcherIfEnabled();
        }
    }

    public int? Day
    {
        get { return _day; }
        set
        {
            _day = value;
            UpdateWatcherIfEnabled();
        }
    }

    public int? Hour
    {
        get { return _hour; }
        set
        {
            _hour = value;
            UpdateWatcherIfEnabled();
        }
    }

    public int? Minute
    {
        get { return _minute; }
        set
        {
            _minute = value;
            UpdateWatcherIfEnabled();
        }
    }

    public int? Second
    {
        get { return _second; }
        set
        {
            _second = value;
            UpdateWatcherIfEnabled();
        }
    }

    public bool Enabled
    {
        get
        {
            return _enabled;
        }
        set
        {
            _enabled = value;
            UpdateWatcherIfEnabled();
        }
    }

    private int? _year;
    private int? _month;
    private int? _day;
    private int? _hour;
    private int? _minute;
    private int? _second;
    private bool _enabled;
        
    private ManagementEventWatcher _watcher;

    public event EventHandler<DateTimeElapsedEventArgs> Elapsed;

    public DateTimer()
    {
    }

    public DateTimer(int? year = null, int? month = null, int? day = null,
        int? hour = null, int? minute = null, int? second = null)
    {
        _year = year;
        _month = month;
        _day = day;
        _hour = hour;
        _minute = minute;
        _second = second;
    }

    private string BuildQuery(int? year, int? month, int? day, int? hour, int? minute, int? second)
    {
        List<string> parts = new List<string>();

        if (year != null) parts.Add("TargetInstance.Year = " + year);
        if (month != null) parts.Add("TargetInstance.Month = " + month);
        if (day != null) parts.Add("TargetInstance.Day = " + day);
        if (hour != null) parts.Add("TargetInstance.Hour = " + hour);
        if (minute != null) parts.Add("TargetInstance.Minute = " + minute);
        if (second != null) parts.Add("TargetInstance.Second = " + second);

        string query = @"
SELECT * 
FROM __InstanceModificationEvent 
WHERE TargetInstance ISA 'Win32_LocalTime' 
AND 
( " + string.Join(" AND ", parts) + ")";

        return query;
    }

    private void HandleEventArrived(object sender, EventArrivedEventArgs e)
    {
        var elapsed = Elapsed;
        if (elapsed != null)
        {
            var instance = (ManagementBaseObject)e.NewEvent["TargetInstance"];
            var dateTime = new DateTime(
                (int)(uint)instance["Year"],
                (int)(uint)instance["Month"],
                (int)(uint)instance["Day"],
                (int)(uint)instance["Hour"],
                (int)(uint)instance["Minute"],
                (int)(uint)instance["Second"]);

            var args = new DateTimeElapsedEventArgs(dateTime);
            elapsed(this, args);
        }
    }

    private void UpdateWatcherIfEnabled()
    {
        if (_enabled)
        {
            if (_watcher != null)
            {
                _watcher.Stop();
                _watcher.EventArrived -= HandleEventArrived;
                _watcher.Dispose();
                _watcher = null;
            }

            if (Year != null || Month != null || Day != null ||
                Hour != null || Minute != null || Second != null)
            {
                var query = BuildQuery(Year, Month, Day, Hour, Minute, Second);
                _watcher =
                    new ManagementEventWatcher(new WqlEventQuery(query));
                _watcher.EventArrived += HandleEventArrived;
                _watcher.Start();
            }
        }
    }

    public void Start()
    {
        _enabled = true;
        UpdateWatcherIfEnabled();
    }

    public void Stop()
    {
        _watcher.Stop();
        _watcher.EventArrived -= HandleEventArrived;
        _watcher.Dispose();
        _watcher = null;
    }

    public void Dispose()
    {
        Stop();
    }
}

Example.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Management;

class Program
{
    static void Main(string[] args)
    {
        var now = DateTime.Now;
        Console.WriteLine("The time is now {0}", now);
        var aCoupleSecondsLater = now.AddSeconds(10);
        using (var timer = new DateTimer(day: aCoupleSecondsLater.Day,
                                            second: aCoupleSecondsLater.Second))
        {
            timer.Elapsed += timer_Elapsed;
            timer.Enabled = true;

            Console.WriteLine("Press any key to exit . . .");
            Console.ReadKey(true);
        }
    }

    static void timer_Elapsed(object sender, DateTimeElapsedEventArgs e)
    {
        var timer = (DateTimer)sender;
        timer.Second = e.DateTime.AddSeconds(2).Second;

        Console.WriteLine(e.DateTime);
    }
}