You could add a LastUpdated field to your table, put logic in your form's
BeforeUpdate event to set that field in the record being updated, then run a
query to get the maximum LastUpdated value from your table.
If you're not using a form for your updates, then there's no way.
I was going to use a variation of the approach you suggested, but I thought
there might be some hidden table property that might contain the information!