Need some help with OPKs

Meg
This is my second month using OPKs and I want to make sure I'm doing this right. We have been following the sperm meets egg plan, where you BD every other day until you get a positive OPK and then three days straight after that.
Well last cycle I never got a positive OPK, I had dark lines on CD 11, but never as dark as the control line. Then I proceeded to ovulate on CD 12, which was confirmed by temping. After this my lines of course got lighter. 
The thing is I usually don't ovulate until on or between CD 14 - 16, so I didn't pay much attention to the dark lines on CD 11.  It seemed too early, so was expecting them to darken even more, but instead I missed my surge and ovulated early. 
Today I'm CD 10 and my OPKs are getting dark again. The first one I took this afternoon around 1pm and the second one I took around  6:15 this evening (picture was taken about 10 minutes after the second test). Does it look like my surge might happen soon? We BD yesterday morning and are supposed to be skipping today, but now I'm wondering if we should BD tonight too, just in case?