When to test.

I've been wanting to get pregnant for a while now, so a guy friend and I BD the weekend before last on Sunday. I knew my period was bound to start that week so I was probably going to be out this month until my period passed and I ovulated (which was supposed to be this week.)

I'm nine days late ( i don't think I'm pregnant, just probably stress,) but if by some miraculous happenstance I did become pregnant that Sunday night, I would have to wait until when my period is supposed show up again at the end of the month, right?

Just want to know for sure so I can strike myself out this month and try to readjust when I might ovulate and know when to try again since I'm late.