Clomid and OPKs

So this was my third round of clomid. Took it day 5-9 of my cycle. This is my first month tracking my bbt also which is jagged and all over the place. I started to take my OPKs last night using the clear blue advanced ovulation kits. I got a empty circle- "low" fertility. This morning I got a solid smiley- the "peak" day.... Did I start testing too close to ending clomid? Or is this correct? I'm on day 12 and got a positive. We BD'd before work just in case it's true but I've never ovulated this early. Any thoughts ?