Even with current knowledge, we’re not really omniscient about what happened in the past. I know the Romans were good record-keepers (I’m not sure how good), but I would be surprised if there weren’t at least some errors and omissions in the small details.
If we did have omniscient knowledge, I would suggest that the situation might be most analogous after several years—when you could still make predictions with high accuracy, but never really being sure that something you’ve done has slightly changed the dates or other details of specific events.
Even with current knowledge, we’re not really omniscient about what happened in the past. I know the Romans were good record-keepers (I’m not sure how good), but I would be surprised if there weren’t at least some errors and omissions in the small details.
If we did have omniscient knowledge, I would suggest that the situation might be most analogous after several years—when you could still make predictions with high accuracy, but never really being sure that something you’ve done has slightly changed the dates or other details of specific events.