The First Response™ 14 Day Ovulation Prediction Test Kit detects the LH surge in urine, signaling that ovulation is likely to occur in the next 24 - 36 hours.
If you have intercourse within the next 24-36 hours after detecting your surge, you will maximise your chances of becoming pregnant. 
First Response™ Ovulation Tests are 99% accurate¹ in predicting ovulation and can be used at any time of the day with fast and easy to read results.

Researcher and Sponsor: Church & Dwight Co., Inc. USA
¹Study protocol #549: First response Ovulation assessment of the inter and intra device precision conducted by Church & Dwight Co.Inc.(2018). https://firstresponsepregnancy.com.au/our-products/complete-planning/

Church & Dwight Co. Inc. conducted laboratory testing on three batches of First Response Ovulation Predictor tests to determine performance of the device. The study utilized LH standards of known concentrations prepared in LH non-surge urine pool. Each batch of First Response Ovulation Predictor were tested in replicates of twenty and with urine standards containing known LH concentrations (20-150 mIU/mL). The results obtained gave 100 % surge at 40 mIU/mL and above for all three batches. The non- surge results for all three batches at a concentration of 20mIU/mL and below is at 100 % for all devices. For more information, please contact Church & Dwight for copy of the study.

ALWAYS READ THE LABEL AND FOLLOW THE DIRECTIONS FOR USE.