when to start testing with OPK and how to feel my cervix

Ginny
Today is my CD8 and I'm wondering when to start testing for my LH surge. I haven't used an opk before and I have the clearblue brand opk. It came with 10 tests. What day should I start testing? I typically have a 26 day cycle.
Also, I have tried checking the position of my cervix a few times and I don't think I can feel it. Does anyone have tips for finding the cervix?