Dollar store ovulation test

Kristy • After ttc for 9 months, we are finally pregnant. 😊 Due April 21, 2016. 💕
Just got off of birth control a month ago and my period was irregular this cycle (8 days late and only lasted 4 days). Ive never had an irregular cycle before. I wanted to try using ovulation test to see if im even ovulating yet. Anyone use the dollar store brand and have success? Since my period is irregular I dont rlly know what day to start using them so im gonna need a good bit...