New to TTC... do OPK lines gradually get darker?

Hi all,

I purchased a bulk pack of PregMate ovulation test strips and tested for the first time just now. I understand that if the test line is as dark or darker than the control line, that indicates a LH surge.

Do the lines gradually get darker the closer you get to LH surge/ovulation?

I know it’s possible to ovulate without a period as well as ovulating shortly after getting off hormonal birth control (I have 2 friends this has happened to - crazy!). So I’m wondering if this is happening to me?

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A little background...

I just got off birth control implant (Nexplanon) 4 days ago on 10/1. I was told fertility could return very quickly, but my cycles can be sometimes irregular so I wanted to start LH testing to see if I could try to get an idea of a cycle.

My period was also estimated to arrive about 10/1 but no sign of it still (I feel the implant removal might have messed with it?). That is also why it says CD35 on the screenshot below.

Thank you!