positive opk cd 6???

Yasemin • Married to wonderful hubby! Have two gorgeous girls 16 and 9. Trying for number 3.
Can this really happen? I'm getting a surge in cd 6 I just finished AF and it's the last bits  coming out like the brown blood but I got a positive surge today. I tested yesterday and it was almost but today it's positive. Has anyone experienced this?can this really happen? I have between 28-30 day cycles so to ovulate this early ? Please any input is appreciated!