Hello when you do onestep OPKs (the cheap ones from amazon), do you look at the result after 10 mins or 30 mins? It says on the back “positive results may be found within 1 minute but to confirm a negative result, the full reaction time of 10 mins is required. Results obtained after 30 mins may be considered invalid”. I just did a test and after 10 mins the second line was quite light but checking again just before 30 mins the second line is nearly as dark as the control line so these are very different results! Which reading should I consider valid?!