EWCM can appear for some women in the few days before O.

I don't believe there are any problems with O'ing on CD11. A normal LP can be up to 16 days in length. Normal variation is from 11 to 16 days.

More likely you will O later than CD11 and the EWCM is a sign that O is just around the corner in the next few days. (so get busy !!)

HTH
TICKLISH