New at TTC

I just started using the <a href="">Glow app</a> and my husband and I are about to TTC. I had Mirena in for a year an a half. I got it taken out 2.5 weeks ago. I did not have a period at all in that time. I’m on the 5th and final day of my period now so I’m excited to TTC during the next fertile window. Since I’ve only logged this period so far, I’m not sure if Glow will be able to accurately tell me when I’m ovulating. I’ve got an OPK, but does anyone have any advice on when to use the OPK? This all just so new to me and after some research I’m a little confused. Any advice would be greatly appreciated!