Brandie,
I'm not going to be much help here as I never had any luck with OPK's, but women with normal cycles should start testing at about CD 9 or 11 (I think) and since you are taking clomid you should probably start within a few days of taking your last pill. They say you should ovulate within 5 to 9 days after your last pill, so you may need to stock up on tests.
Good Luck