What kind of control?
If a variable: Set Variable [$$Date ; value: Get ( CurrentDate ) ]
If a field: Set Field [YourTable::DateField ; Get ( CurrentDate ) ]
Both of these can be in a script performed by the OnLayoutEnter script trigger found in Layout Setup.
Or you can use the Insert Menu while in layout mode to insert layout text on your layout that will always display the current date and not need any script at all.