OPK question

iVillage Member
Registered: 02-17-2002
OPK question
Tue, 01-27-2009 - 10:17am
Do OPKs usually get gradually darker and darker or can they go from really light to positive from one day to the next? By my estimations I should be ovulating Thurs. or Fri. I started doing OPKs a few days ago - the first one there was no second