Ovulation Test Strip detects the existence of Luteinising Hormone in your body.
Luteinising Hormone is always there in the body but when you are close to Ovulation it gradually increase...

The NORM is, if a person having a 28 day cycle, she should Ovulate on the 14th Cycle day.
And it is advised to start testing from Cycle Day 9.

Initially you may see a Negative Reading. ( Test Line is Light Red Colour / Not to be seen, where as Control Line is Red Colour)

Around Cycle Day 11 or 12 you may see the Test Line turning dark and SAME colour as the Control Line. (Positive Reading)
That is the beginning of your Fertile Window! Good time to try for a baby...

And around Cycle 12 or 13 you may see the Test Line DARKER than the Control Line. ( PEAK Reading) This mean you are about to ovulate in the next 12 to 48 hours... This is the Most Fertile Period.

High level of Luteinising Hormone will help to release ( PUSH) the egg from the ovary.. Which means you will be Ovulate in next 48 hours after you see the PEAK reading..

It is advised to test between 10am to 9pm. Once a day initially and twice a day as you get closer to Estimated Ovulation Day.. So you will not miss the Peak Reading.

However it is better to try for a baby as and when you see the Positive Reading. A healthy sperm can stay in a girl's body upto 5 days and starting early will give you better chance to conceive.

Also once you are Ovulated the egg will be there for 24 hours..
So you will have good enough time....

Most importantly stay Calm and Relaxed while Trying for a baby...

 As this is your First Cycle using Ovulation Test Strips, start testing little early. It will help you give a better picture of how things work...

After you see the Peak Reading gradually the Test Line will turn Lighter day by day...

I hope you understood.. if you have any questions please feel free to contact me anytime....