when is the right time

So my calendar tells me I should have started my period yesterday and the last couple of months I've started right on that prediction date or 1-2 days before but this month no symptoms of my period.. usually I'm a heavy bleeder and lots of cramping back pain very emotional but this week I've had nothing but I don't feel pregnant either.. how long should I wait after a missed period to take a test? I just don't want to do it too early and get discouraged if it turns out to be a negative. I just want to know when I should take a test for the most accuracy..