How to Export WPF DataGrid (SfDataGrid) to Excel that hasn't Loaded?

private static void OnExecuteExportToExcel(object sender, ExecutedRoutedEventArgs args)
{
    var dataGrid = args.Source as SfDataGrid;
    EccelOptionsConverter ExcelOption=new EccelOptionsConverter();
    if (dataGrid == null) return;
    try
    {
        var options = args.Parameter as ExcelExportingOptions;
        ICollectionViewAdv view;
        ExcelEngine excelEngine = new ExcelEngine();
                
        options.ExcelVersion = ExcelVersion.Excel2010;
        options.ExportingEventHandler = ExportingHandler;
        if (!ExcelOption.isCustomized)
            options.CellsExportingEventHandler = CellExportingHandler;
        else
            options.CellsExportingEventHandler = CustomizeCellExportingHandler;
 
        dataGrid.ApplyTemplate();
 
        excelEngine = dataGrid.ExportToExcel(dataGrid.View, options);
 
        var workBook = excelEngine.Excel.Workbooks[0];
 
        SaveFileDialog sfd = new SaveFileDialog
        {
            FilterIndex = 2,
            Filter = "Excel 97 to 2003 Files(*.xls)|*.xls|Excel 2007 to 2010 Files(*.xlsx)|*.xlsx",
            FileName = "Book1"
        };
 
        if (sfd.ShowDialog() == true)
        {
            using (Stream stream = sfd.OpenFile())
            {
                if (sfd.FilterIndex == 1)
                    workBook.Version = ExcelVersion.Excel97to2003;
                else
                    workBook.Version = ExcelVersion.Excel2010;
                workBook.SaveAs(stream);                        
            }
 
            //Message box confirmation to view the created spreadsheet.
            if (MessageBox.Show("Do you want to view the workbook?", "Workbook has been created",
                                MessageBoxButton.YesNo, MessageBoxImage.Information) == MessageBoxResult.Yes)
            {
                //Launching the Excel file using the default Application.[MS Excel Or Free ExcelViewer]
                System.Diagnostics.Process.Start(sfd.FileName);
            } 
        }                                              
    }
    catch (Exception)
    {
 
    }
}