cheesycake: for me, i started to use OPK from day 12 onwards, coz my past four mths shows dat i "O" between CD12-19..there were a few mths I "O" late so my AF also late, i.e my CD is between 28-30..but between OPK +ve to CD1 is almost always 14days (there is one mth 13 days) then i combined with BBT and for my case, after OPK +ve, 1-2 days later then temp dip and shoot up again, so i believe abt to O liao but once OPK +ve, I BD for consecutively 3-4days.
Wannababy: last time, i go for health screening (women's) first for a general idea abt whehter i got any problem..then later with the results I visit the TCM..