Do you track ovulation day?

So I have tracked my ovulation day for 2 months. The first month it happened on CD 15, no symptoms but just faintly some EWCM and a positive opk leading to it. Second month I tracked I had bright blood spotting, and lots of cramps on cd 10. Period followed 12 days later so I think my guess that I had ovulated before I got my OPKs on CD13 was accurate. I’m about to finish my period and if I buy the 10 day pack, do you think I will have enough? Does ovulation day normally stay fairly consistent (my periods are very regular) or does it always bounce around? Just trying to make an educated guess for those who track their ovulation day with opk or BTT