Execute a function in a specific second in VB.NET - vb.net

Question

I'm making a backup scheduler of my files, using a Timer, and it executes when the said time is equal to the current time, But my problem is it keeps on executing until 1 sec has passed like what i do when i use MsgBox.
This is what i have tried and it's not working, it still executes until 1 second has passed. Please help me achieve that. Thanks!
Dim d As Date = DateTime.Now
Dim d1 As Date = d.AddMilliseconds(1)
Dim dw As String = d1 & DateTime.Now.DayOfWeek.ToString
Dim date2 As Date = cntrl.Value.AddMilliseconds(1)
If Form3.chkWed.Checked = True Then
If dw = date2 & Form3.chkWed.Text Then
CopyStart(src, dest)
End If
End If
If Form3.chkThu.Checked = True Then
If dw = date2 & Form3.chkThu.Text Then
MsgBox("P")
End If
End If

Answer 1

What I'm talking about is something like the following. In this example, there are three RadioButton controls that indicate that a task should be initiated at 1.00 PM, 5.00 PM and 9.00 PM respectively.
Private Sub RadioButton1_CheckedChanged(sender As Object, e As EventArgs) Handles RadioButton1.CheckedChanged
'The next task is to start at 1.00 PM
Me.ResetTimerInterval(TimeSpan.FromHours(13))
End Sub
Private Sub RadioButton2_CheckedChanged(sender As Object, e As EventArgs) Handles RadioButton2.CheckedChanged
'The next task is to start at 5.00 PM
Me.ResetTimerInterval(TimeSpan.FromHours(17))
End Sub
Private Sub RadioButton3_CheckedChanged(sender As Object, e As EventArgs) Handles RadioButton3.CheckedChanged
'The next task is to start at 9.00 PM
Me.ResetTimerInterval(TimeSpan.FromHours(21))
End Sub
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
'The next task will start in 24 hours.
With Me.Timer1
.Stop()
.Interval = Convert.ToInt32(TimeSpan.FromHours(24).TotalMilliseconds)
.Start()
End With
'Start a task right now.
Me.InitiateTask()
End Sub
Private Sub ResetTimerInterval(nextTaskStartTime As TimeSpan)
Dim nextTaskStartDateTime = Date.Today + nextTaskStartTime
If Date.Now > nextTaskStartDateTime Then
nextTaskStartDateTime.AddDays(1)
End If
Dim timeUntilNextTask = nextTaskStartDateTime - Date.Now
With Me.Timer1
.Stop()
.Interval = Convert.ToInt32(timeUntilNextTask.TotalMilliseconds)
.Start()
End With
End Sub
Private Sub InitiateTask()
'...
End Sub

Answer 2

I have added another Timer, and did something like this.
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
Dim dw As String = DateTime.Now & DateTime.Now.DayOfWeek.ToString
If Form3.chkThu.Checked = True Then
If dw = Form3.DateTimePicker1.Value & Form3.chkThu.Text Then
Timer2.Enabled = True
End If
End If
End Sub
Private Sub Timer2_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer2.Tick
Timer2.Enabled = False
MsgBox("P")
End Sub