-- Posted by Anonymous at 12:28 pm on Dec. 31, 2008 how long after having sex will a pregnancy test show up? -- Posted by katjassidekick at 12:28 pm on Dec. 31, 2008 To be most accurate is 19 days. -- Posted by stinaaa at 12:29 pm on Dec. 31, 2008 wait until you miss your period and take it then. Wait even longer for a more accurate test. -- Posted by Points at 12:29 pm on Dec. 31, 2008 Wait for the missed period. -- Posted by fayfayfay at 12:40 pm on Dec. 31, 2008 i thought it was like a week ish