Best OPK

Hey Mommies and Future Mommies my fertile window started yesterday and will last till the 27th. I really wanted to try a ovulation kit this cycle just to make sure I've tried everything I possibly can to get pregnant. I never used an opk and I was wondering if someone can tell me when is the best time to take it and what brand work best? Have anyone had success after using an opk? OMG any advice would be greatly appreciated 😙