How to: Set and Return Dates with the Windows Forms DateTimePicker Control
The currently selected date or time in the Windows Forms DateTimePicker control is determined by the Value property. You can set the Value property before the control is displayed (for example, at design time or in the form's Load event) to determine which date will be initially selected in the control. By default, the control's Value is set to the current date. If you change the control's Value in code, the control is automatically updated on the form to reflect the new setting.
The Value property returns a DateTime structure as its value. There are several properties of the DateTime structure that return specific information about the displayed date. These properties can only be used to return a value; do not use them to set a value.
For date values, the Month, Day, and Year properties return integer values for those time units of the selected date. The DayOfWeek property returns a value indicating the selected day of the week (possible values are listed in the DayOfWeek enumeration).
To set the date and time value of the control
Set the Value property to a date or time value.