I believe the answer according to Weschlers, "Taking Charge of your Fertility" is that we ovulate usually on the last day of EWCM or the first dry day. Does that help?
I think she calls those 2 days our most fertile days.

 

Yes that's what I understand too---the purpose of the EWCM is to help the sperm not only get to the egg as fast as possible (it actually forms long strands--"sperm highways"-- when mixed with male fluid but the EWCM also helps the sperm live longer to maximize the chance of conception. If you are charting you will usually notice a spike in temp the day after the ewcm ends....not all of us get dry at that point though, my cm turns to creamy texture after ovulation occurs.