When you get an LH surge you're not actually ovulating yet. It's the surge that tells your body it's time to ovulate so it takes about another 24-36 hours after an positive OPK for that to happen. However, you don't want to wait until you actually are ovulating to have sex because it takes awhile for the sperm make the long ass (to them) journey up to your fallopian tubes and the egg doesn't live very long. So you want to have sex as soon as you can after getting the OPK. I would trust the OPK regardless of CM and if you're worried about not having the right CM, use preseed. It's awesome. Also, if your CM isn't lining up with your surge, just have sex both times.