on first sheet, am using code:

Option Explicit
Private Sub Worksheet_Change(ByVal Target As Excel.Range)
With Target
If .Count 1 Then Exit Sub
If Target.Row < 56 Then Exit Sub
If Me.Cells(.Row, "A").Value = "." Then Exit Sub
If Not Intersect(Me.Range("BF:BG"), .Cells) Is Nothing Then
Application.EnableEvents = False
With Me.Cells(.Row, "BD")
.NumberFormat = "dd"
.Value = Now
End With
Application.EnableEvents = True
End If
End With
End Sub