Hey Hun,
Thought i would reply here as well, even though i have already PM you.IN case other lovely ladies in the future have the same question.
According to the Ovunow OPKS- the information they provide is:
"test measures luteinzing Hormone (LH), although this is always present in your urine, LH increases just before your most fertile day of your cycle.
This LH surge triggers the release of an egg from one of your ovaries. Most women will ovulate within 24-36 hours after the LH surge is dectected."

I love how they use the term MOST women! Just get ready to attack DH shortly to make sure you cover all time periods!