Ovulation question

Julie
Hay ladies! I need some help here.. So, I had a chemical last month and now I am a bit confused when I will o. My cycle is usually 31 days.. Chemical cycle was 47. I have two apps one with my normal cycle and one with my chemical cycle. Should I just start using opk' on what would have been my normal fertile window.. Or will it be off? What would you guys do?? Thanks