Add Feature to Completed C# WinForms Application

I have a completed c# Windows Form (WinForms) .Net 4.0 application with a datagridview control (that has a number of columns) and some labels / buttons. The application's purpose is to log people going in and out - for front desk security personnel to use. The app can save the datagridview to an excel file automatically and manually. Currently, each time you start the application, an empty datagridview is presented (with pre-formatted column headers). The update I would like to add, will allow the app to load the last excel sheet that was saved upon start-up (up to 200 records). Each work day starts at 7am, so when the program loads, it would have to load the last file that was saved @7am or later. If no previous file exists, then a new file would be created. Another approach, is to just load the last 200 records that was saved, back onto the datagridview control upon start-up. This would always keep the datagridview control with no more then 200 records when newly loaded (whenever someone starts the application). Again, this would only apply when someone starts the application. The app can keep as many records as possible while running. This should be a just single class added to the app.