Question im TTC but???

I need help on when to test . My period last was April 20th . The time before that was march 19th . I'm about 34- day cycle. Off the pill for 8monts now . We're I think I "should conceive April 11th unprotected sex . " question is when to test!!! . And I had spotting 3rd -5th may. very light . What dpo would I be im confused about for this is? Thank you for your comments