I can also surmise from the OP that a time stamp is wanted for when the new record is created. Not sure if that is true though.
Or a time stamp is wanted when approved rather than just a date, in which case you'd want to use approvedDate = Now()
Note that if you don't restrict the records for this form to only unapproved ones, double clicking on the control where there is an existing value will over-write it. Be careful of that.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.