next time you're at the chemist, just ask the ladies there. different tests work different ways. strip tests usually can be used earlier than midsream. there are new digital midstreams too. it depends on how sensitive you want the test to be and how much you're willing to pay. if you're waiting till the day AF is due, then midstreams are good for then and for days after then. strip tests are better if you want to test 7-10 days after ovulation. ask the chemist ladies or even your doctor next time you're there.