Help please charting

I have just started using opk and just need a little advice. When do you start using them in the cycle my last period began 10 days ago I bleed for 5 days. And I have to avoid pregnancy for 2 more months due to a miscarriage I had in April so I am using this time to learn more about charting so in July-Aug when I am able to try again that I kind of know what I'm doing and not just a shot in the dark.