Should I take a test?

My partner and I had unprotected sex Christmas <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">Eve</a>, I wasn't ovulating and was out of my fertile period although I should have started my period three days ago and I haven't had spotting or any other symptoms. Should I wait and see what happens or take a test to be sure?