Quick Question!

Cierra
(Refer to previous post) So if my line is dark on my opk, which is almost as dark as the control line... someone told me that I should start testing twice a day now. 
But the question is, how many hours apart should I? I tested 6am when I woke up. Now what time should I test? 
Also, of these opk lines are correct which I have the Wondo brand from Amazon... glow is slightly off. Glow says I don't ovulate until May 16th (Friday)