Dating and viability scan is done between six and nine weeks of pregnancy, NT scan is done between 11 and 13 weeks, double marker test is done between 8 and 14 weeks, the Quadruple marker test is done between 16th and 18th week. If your pregnancy is within these weeks do the test as directed as women above the age of 30 is considered as an elderly mother who will be at high risk for multiple problems due to which these tests have been asked. Do whichever test you still can as nothing can be done for the tests that you're already past the date. Do visit your OBGYN for further information.