Q: Does ovulation occur on the day of drop or day of rise of temperature?
A: The exact day of ovulation cannot be determined by the basal body temperature ahead of time, but often afterwards. Once your temperature has gone up, you can be certain that the egg cannot be fertilized anymore from sexual intercourse at that time. The egg only lives 12-24 hours, and by the time the temperature has risen, the egg is no longer viable.
The vast majority of women do not have a drop in basal temperature, so that won't tell you much either.
If a couple wants to achieve a pregnancy, a better sign to focus on prospectively is the cervical fluid, not the temperature curve.