Do I do an OPK every day? Do I do it on FMU?

No you don't test with the first wee of the day. Lol I'd start testing as soon as you finish your period. I'm always 28 days and usually ovulate round day 14 this month it wasn't the case, I ovulated on day 6. Which is obviously very early. So I'm very glad that I started testing early you just have to wait longer to see if your pregnant :( good luck to you x