How long after a missed period should i take a pregnancy test its been 3 days im late with period?

Depends on variables: The quality and source of the test can influence the outcome.The first morning urine is probably more accurate than a random one. Respected brand OTC tests are more sensitive than some dollar store products. You may be able to detect a positive as soon as you miss your expected period, but it also may take another week or so to turn positive.