Help to understand positive result

I got two very positive pregnancy tests after only one cycle of trying. That was shocking, especially since I am 39 and trying for #1. I took the tests on the first day that I missed AF. I realize it is still very early and a lot can go wrong. Plus, other conditions can cause hcg rises. Of course, I am assuming everything but a pregnancy is causing a false positive. When is the best time to test again and what should I do in the meantime? Thanks so much!