They can happen before, during and/or after. So unless you add it to other ways of detecting o, it can't tell you too much.
Before: the pain is from the build up of the follicle and the fact that it is close to bursting
During: the pain is from the actual bursting of the follicle
After: the pain is from the reabsorbtion of fluid released when the follicle burst.
I got o pain every month and could usually even tell what ovary the egg was from. However, it never came at the exact same time. I could get it anywhere from 2 days before to 2-3 days after the egg actually popped.
So, it is best to combine o pain with something else, like opks or charts, to pinpoint o.