Long cycle & OPK testing.


I have always had longer cycles, typically 35-40 days.. on what CD should I start testing for ovulation? I already have a 4.5 year old and haven’t been on BC since the end of 2016 & was only on it for 1 month.. We are actually TRYING to get pregnant & I feel like it’s not easy with such long cycles! 🙈. Anyone else have long cycles like this, what was your experience with timing (getting a positive OPK & pregnancy!). Thank you!! <3