Shouldn’t use fmu...
This is taken off baby centre:
‘Instructions may vary slightly depending on which kit you use, but in general you should try to collect your wee between 10am and 8pm. The optimum time is supposed to fall between 2pm and 2.30pm.
Try to collect your wee at about the same time every day, though this is not absolutely necessary. Don’t test your wee as soon as you wake up, because you may miss the first day of your LH surge. Try to reduce the amount of liquids you drink for about four hours before you do the test. Too much liquid will dilute your wee, which could make it more difficult to detect the surge.
Read the results within 10 minutes. A positive result will not disappear, but some negative results may later display a faint second colour band. So throw the test card away once you’ve read the result.’
Hope this helps, I’ve never noticed mine get darker as I get closer to ovulation, they’re just 100% positive when I am, no mistaking it x