I have two date pickers for users to select a from-to range.
I want the default 'from' date to be today -30 days, and the 'to' date to be today (hour included).
How do I do this?
There is no "default" date per se. The control shows the date associated with its current value so you need to set the Value in xaml or in code to a given date. In code would probably be the easiest thing - e.g. this.startDate.Value = DateTime.Today.AddDays(-30);. In you need to do this in xaml you could probably write your own custom MarkupExtension that returns a date given some offset or do a onetime binding to a static property that you expose.