8 days and my period has not come yet. have lower back pain, breast tenderness, headaches, fatigue. how long should you wait to take a pregnancy test?

Now is a good time: It can be hard to guess whether a woman is pregnant or not. A home urine pregnancy test gives a very reliable result 3 weeks after sex (3 weeks after when conception might have occurred), 1 week after missing a period, or after having a "weird" period. If done sooner, a positive result is likely real, but a negative result may be due to testing too soon, and thus lead to a repeat test.