Opk testing?

Anna • Had our first baby in July 2016, now we are due with baby #2 due January 2018. Over the moon with love and joy for These two little miracles 💕
I am just trying to get some advice. Do you test only in your fertile window until you get a positive? My fertile window starts tomorrow and I don't know if I should start testing a few days before and stop testing when a few days after glow says?? I started opk testing last month but didn't do it every day. Just looking to see what other women are doing. Thank you!