Dim difference As TimeSpan
        Dim Termin As Date
        Dim today As Date = today
 
        Try
            For rowIndex = 0 To InventartabelleDataGridView.RowCount - 1
                Dim theDate As Date = DateTime.ParseExact( _
                  InventartabelleDataGridView.Rows(rowIndex).Cells( _
                  "naechsteInventurDatum").Value.ToString, "dd.MM.yyyy", _
                  CultureInfo.InvariantCulture)
 
                difference = today.Subtract(Termin)
                If InventartabelleDataGridView.Rows(rowIndex).Cells( _
                  "naechsteInventurDatum").Value IsNot Nothing Then
                    InventartabelleDataGridView.Rows(rowIndex).Cells( _
                    "colImg").Value = Signale_20x20.Images(3)  'Warndreieck
                ElseIf difference.Days <= 5 Then
                    InventartabelleDataGridView.Rows(rowIndex).Cells( _
                      "colImg").Value = Signale_20x20.Images(1)  'Gelb
                ElseIf difference.Days > 5 And difference.Days <= 10 Then
                    InventartabelleDataGridView.Rows(rowIndex).Cells( _
                      "colImg").Value = Signale_20x20.Images(2)  'red
                Else
 
                End If
 
 
            Next
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try

Public Class frmDGVDateIcon
 
    Dim bs As New BindingSource
    Dim WithEvents dgv As New DataGridView With
        {.Parent = Me, .Size = New Drawing.Size(300, 300), .DataSource = bs}
    Dim dt As New DataTable
 
    Dim dateok, nodate As Bitmap
 
 
    Private Sub frmDGVDateIcon_Load(sender As Object, 
                       e As EventArgs) Handles MyBase.Load
 
        'Einige Demo-Daten
        dt.Columns.Add("Date", GetType(DateTime))
        dt.Columns.Add("Icon", GetType(Bitmap))
 
        With dt.Rows
            .Add(Nothing, Nothing)
            .Add(New DateTime(2020, 12, 10), Nothing)
            .Add(New DateTime(2020, 12, 13), Nothing)
            .Add(Nothing, Nothing)
            .Add(New DateTime(2020, 12, 16), Nothing)
        End With
 
        'Datenbindung herstellen
        bs.DataSource = dt
        dgv.Columns("Icon").MinimumWidth = 16
 
        'Zwei Bitmaps für die Icon-Spalte erstellen
        nodate = New Bitmap(16, 16)
        Using g As Graphics = Graphics.FromImage(nodate),
            pn As New Pen(Color.White)
            g.Clear(Color.Red)
 
            g.DrawLine(pn, New Point(0, 0), New Point(16, 16))
            g.DrawLine(pn, New Point(16, 0), New Point(0, 16))
        End Using
 
        dateok = New Bitmap(16, 16)
        Using g As Graphics = Graphics.FromImage(dateok),
            pn As New Pen(Color.Black)
            g.Clear(Color.Green)
            g.DrawLine(pn, New Point(0, 0), New Point(16, 16))
        End Using
 
    End Sub
 
 
    Private Sub dgv_CellPainting(sender As Object,
        e As DataGridViewCellPaintingEventArgs) Handles dgv.CellPainting
 
        If (e.RowIndex >= 0 And e.RowIndex < bs.Count) 
            AndAlso e.ColumnIndex = 1 Then
 
            'Gebundene Datatable-Zeile casten
            Dim r As DataRow = DirectCast(bs(e.RowIndex), DataRowView).Row
 
            'Icon-Zelle zeichnen
            e.PaintBackground(e.CellBounds, True)
 
            'Icon in der Zelle zentrieren
            Dim lft As Integer = 
                e.CellBounds.Left + (e.CellBounds.Width - 16) \ 2
            Dim tp As Integer = 
                e.CellBounds.Top + (e.CellBounds.Height - 16) \ 2
 
            'Icon-Spalte abhängig vom Eintrag in der Date-Spalte zeichnen
 
            If IsDBNull(r("Date")) Then
                e.Graphics.DrawImage(nodate, lft, tp)
            Else
                e.Graphics.DrawImage(dateok, lft, tp)
            End If
 
            'Icon-Zelle als bearbeitet melden
            e.Handled = True
        End If
    End Sub
End Class

  ' Symbole setzen wenn Datum (Termin) nicht eingetragen oder überschritten 
  ' wurde bzw. Termin veraltet ist
        Try
            For rowIndex = 0 To InventartabelleDataGridView.RowCount - 1
                Dim s As String = InventartabelleDataGridView.Rows( _
                  rowIndex).Cells("naechsteInventurDatum").Value.ToString
                Dim d As Date
                If InventartabelleDataGridView.Rows(rowIndex).Cells( _
                  "naechsteInventurDatum").Value IsNot Nothing Then
                    InventartabelleDataGridView.Rows(rowIndex).Cells( _
                    "colImg").Value = AB_Images(5)  'Warndreieck
                End If
                If Date.TryParseExact(s, "dd.MM.yyyy", New _
                  Globalization.CultureInfo("de-DE"), _
                  Globalization.DateTimeStyles.None, d) Then
                    ' korrekt
                    If (Now - d).Days < 4 Then
                        InventartabelleDataGridView.Rows(rowIndex).Cells( _
                          "colImg").Value = AB_Images(3)  'Gelb
                    ElseIf (Now - d).Days < 5 Then
                        InventartabelleDataGridView.Rows(rowIndex).Cells( _
                          "colImg").Value = AB_Images(2)  'red
                    Else
 
                    End If
                End If
            Next
 
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try