When Should You Take Pregnancy Test?

Chelsea • I am 23, married to the man of my dreams since March 7, 2014 & trying for our first baby Herrington since February 2016!
How many DAYS PAST OVULATION? Can't go by my cycle because it's really irregular, but I do know that I got a positive ovulation test on CD 20, so just wondering how many DPO I can test & get an accurate result. :)