one of the things you can drop onto a form ( like you drop a text box) is a timer. You would also need to create an action listener for your timer. i'm not sure on details of adding controls on the fly to a form, but you should easily be able to switch the visible status.
sounds like i fell into java syntax with 'action listener' but you click the lightning bolt in the control properties thing and add essentially a listener for your timer control. i wrote mine out in code first then linked it through that lightning bolt. google c# timer maybe get all the info you need.