New to BBT

So I just started tracking my bbt and I don't want to miss my ov but don't when I'm supposed to BD. I know it's best to BD just before OV but this being my first chart I'm not sure if I am about to OV or if maybe I already did. My temp took a little dip this morning and my CM increased but is still not egg white. I guess what I'm trying to ask is, does your temp go down just before OV and then go up after OV or am I mixing up my info? I'm so confused. :(