How long after a missed period should you take a pregnancy test?

I don't think  is the best site to ask this sort of question. Try getting in touch with someone in the medical field for a truly accurate answer. The best I can share with you is that a period can be "missed" or "late" for many reasons. This includes diet, stress levels, hormones, etc. Think about your latest eating habits. A lot of acids, such as lemon juice, can delay a period. Have you been stressed? Worrying about a pregnancy may cause your period to come even later, and that won't help you much. I suggest taking a pregnancy test 4 days after a supposed missed period due to the hormone HCG doubles essentially every 2-3 in early pregnancy. This is the hormone a pregnancy test attempts to detect. Take it in the morning, when levels are highest. Also, visit a doctor to be sure of what's going on with your body. 

Yes she should but is this a question?