It's going to involve a little bit of scripting no matter what product you have; I just learned how to do it in Indusoft Web Studio with VBScript. Meanwhile, FTView will let me programmatically set object focus with VBA but IWS won't.
In FactoryTalk View your toolset is VBA and the System tags. The Object Model does not appear to include a timestamp as a property of the Numeric Input or the Button or the Tag object. VBA has a perfectly good set of basic Now(), Date() and Time() functions.
Is your parameter changed by a Numeric Input object, or by a pushbutton action, or by something else like a radio button or checkbox ?