How late should you be before you test?

Since using Glow, my AF almost always comes on time. Last month, I was about 3 days late then she came. This month I was due on the 19th and she still is no where in sight! I'll admit sometimes I feel like when I think about it or finally check my app to see I'm late, it seems she comes and its heart wrenching at minimum. However, this time I feel hopeful. I haven't been focusing on conceiving as much as normal so much that I'm just now realizing I'm over a week late. I just got a new job and maybe that stress kind of took a toll on me. DH and I have been TTC for over 3 years now.