You could use the macro HideRowValue() for this
Sub HideRowValue( strSheetName As String, iColumnIndex As Integer, oValueToHide, Optional bFindAll As Boolean )
REM	This hides a Row in Calc if it contains a specific value inside a particular Column.
REM <strSheetName>:	The name of the Sheet containing the Column with index=iColumnIndex.
REM <iColumnIndex>:	0-based index of the Column that holds the values to check.
REM					( the values in this Column should be of the same Type as the value to hide ).
REM <oValueToHide>:	If this value is found in the cell, then the entire Row will be made hidden.
REM <bFindAll>:		True = Hide ALL occurences; False = Hide only the first occurence.
	Dim oSheet : oSheet = ThisComponent.Sheets.getByName( strSheetName )
	
	REM Traverse Rows:  99999= set here your maximum number of Rows to check...
	For i = 0 to 99999
		oCell = oSheet.getCellByPosition( iColumnIndex, i )
		If oCell.Value = oValueToHide Then
			oSheet.Rows.getByIndex( i ).isVisible = False
			If Not bFindAll Then Exit Sub
		End If
	Next i
	
End Sub
in your case you could call something like  HideRowValue( "Sheet1", 0, CDate("17-04-2015") )
Then you could connect it to the Sheet Event “Activate Document”.