First response ovulation kit

Need to know if this means I'm going to ovulate in the next 24-36 hours. I was planning on going to have sex tomorrow probably in the am. Then Monday and possibly Wednesday. I should be good right ? I wasn't going to buy an ovulation kit this month since I know I ovulate around the 18th day but someone told me it changes month to month. I'm still going to take another test tomorrow to make sure. So any ideas about this test. Still want to know about this test