ovulation help?

Ana • 19| 11.17.2014💕| TTC #1👶🏻
This is my ovia cycle, around what day should I start checking for ovulation? Last month I got it right on the head and it was 15 days after but the next feat it was gone so I think I missed it by a little. My cycle is around 32-36 days. Me and my boyfriend have been trying for 4 months now😊