Assigning default values to properties

Hello..

I have created a Silverlight application with CSLA. I want to assign default values to some of the BusinessBase class's properties, which are not bound to the UserControls.

eg: 1] SysDate - The current datetime should be assigned to it.

2] UserId - The current user's id should be assigned to it.

These fields are not bound to UI.

So, where should I assign these values in BusinessBase class?

Or what is the best practice for handling such type of issue?