Is there a rule against using OPKs after 8pm?

This is my first time using and my instructions are to test between 10am and 8pm and I usually test after 10am and after 5pm…HOWEVER…I had a softball tournament today and forgot to take my tests with me 🤦🏻‍♀️ I got home a little after 8 and took one and it was positive.

We will obviously BD tonight, but I wanted to know if there was a rule against testing after 8? Like could it be a false positive? This is my first positive I’ve gotten and I’m on CD16.

Please help me!