Period is due tomorrow, 4 hpt's say positive. When should I get the blood test done? When will it be most accurate? Is monday too early?

You are pregnant. You do not need the blood test. You are pregnant. Your OB may send it just for pro forma or tradition along with other prenatal labs. But, there is no need to date the next test or wait any longer. Four positive tests are impossible to be wrong. I am not sure why you keep asking questions or doing more expensive tests. I see no reason to be spending money when the results of the test are known.