I used to have 35 day cycles so I would ovulate around day 21, so I would think you'd ovulate around day 19, but you'd probably want to start to test abit earlier to be on the safe side. Are you charting/keeping an eye on your cm? I definitely recommend that you do, this is my first month ttc so still learning my stuff but I found my cm noticeably changed as I neared ovulation, it went to wet to very very wet, to ewcm and the day I had loads of ewcm I got my positive opk. I was told to test morning and night, but if you can't then its best to test in the afternoon apparently as first thing in the morning you can miss the surge. I was reading about the SMEP technique and that sounds quite good (google it if you need more information). I haven't tried temping and I dont think I will, as I feel Im getting very clear signs through my cm changes.