You spotted 4 days before period due then you found out pregnant what date should you give as first day of your last period?

In this case, you would typically give the first day of your last period as the date when your period was originally due, not the spotting date. Since you spotted 4 days before your expected period, you would count back to that day, which would be the first day of your last menstrual period (LMP). This is usually how healthcare providers calculate gestational age and due dates.