when do i ovulate?

i have v regular 28-29 day cycles with occasionally a day late or early, if this is accurate how good are my chances this month? if my period comes on the 29th day of the cycle, does that mean i DID ovulate on christmas? no i do not track ovulation any other way i work a lot so i don’t have the time to keep track of everything, jus curious based off of this alone. ps i know that ovulation can occur later or earlier but just curious!