Well,we did it around day 9,since my cycles are usually over 30 days.Then we did it every 2 days (days 9,11,13) then we bd'd on CD15,16,17 and 18,since I was pretty sure I O'd between CD17 and 18.We switched out a few days here and there,but the last 3 days were very important.
We didn't use opk's all the time,since we didn't have any anymore,and couldn't get some in time.But I went off other O symptoms too.Drank lots and lots of water to help with EWCM,since I don't get a lot of that.