Diazepam takes time to be absorbed in the body and a lot of time to be eliminated as well. Its half-life is 20 to 100 hours. It means that if you've taken 5mg of Diazepam, it will take 20 to 100 hours to have 50% of it in your blood. For it to be considered insignificant, it will take about 100 to 500 hours or 4 days to 20 days.
I hope this helps.