opk questions. please help! thanks

I'm looking at getting some ovulation tests for the next cycle. We've only been ttc for one month so I'm a newbie. My questions are, which do you recommend? & what exactly is the point? I know that it's to detect ovulation, but my cycles are mostly regular. Sometimes I'll be late or early by a couple days. But if we have sex everyday in my fertile window do I really need an ovulation test? I'm not sure if that made sense haha anyway...any help you can give me is greatly appreciated! Thanks!!