"The day that the OPK turns positive may be your last fertile day because of the delay that occurs before the LH shows up in the urine."
Dear Dr. Walmer,
I'm confused by your statement above, because in the instructions for my LH OPK strips (Wondfo), it says the best timing of intercourse is AFTER 24 hours, but no later than 48 hours, of your OPK . The timing seems to be critical, but there is so much conflicting advice out there.