Help? New to OPK

This is my first time using an opk. I just started using them yesterday. For some reason I can't share screenshots, but the test I took yesterday read as a low 0.77

Today, the test line is obviously darker than the control line and the premom app says it reads as a high 1.29 (attached picture).

So am I close to ovulating or am I already ovulating? Is it normal for there to be such a big difference in tests in only 24 hrs? I'm not too sure how to read these tests or how they work just yet.