Hide site header when sticky menu active

My site header/primary nav takes up the first almost 100 pixels on the top of my page. I have enabled a sticky menu once you start scrolling down. It is smaller with a height of 40 pixels. The result is that when you start slowly scrolling down, at the beginning you will the sticky menu appear over the top of the other menu. How can I get either (1) the sticky menu only enabled once you scroll down past the regular site header, or (2) the site header to disappear once the sticky menu appears? That way you wouldn't see both menu bars at the same time. Thank you!