Is it true ?

Is it true that there could be a possibly chance that you could get pregnant the day before your actual ovulation day ? My ovulation day is actually is tomorrow but I had intercourse Sun Mon and yesterday. The glow app said my ovulation day is tomorrow but when I used the ovulation calculator on different websites they are telling me it's Thursday and not tomorrow. If it is Thursday and I don't have intercourse tomorrow because I'm going by the glow app is there still a possibility me of becoming pregnant ?