Take a test most tests can detect before you missed period. Make sure it reads level detected down to 25
if your late you can take a test. most test now say they can detect it up to 3-5 days before your period.
Pregnancy test say wait a week (7days) before taking a home pregnancy test, If it were me I would wait 7 days then take a pregnancy test. If nothing results from that then wait another 7 days and take another. The pregnancy boxes give you all that info on the back of the box.