How long do i need to stop smoking before a cotinine blood test?

Depends....: At least more than 2wks..........but there is genetic and individual variations.

How heavy was use?: “When someone stops using tobacco & nicotine products, it can take more than 2 weeks for the blood level of cotinine to drop to the level that a non-tobacco user would have & several weeks more for the urine level to decrease to a very low concentration.” REF: http://labtestsonline.org/understanding/analytes/nicotine/tab/test/