When was the Original Organization XIII created?

So, I was thinking how the Org XIII only had 13 members for a total of a week and a few hours out of many years of existance, but that led to the question of: How long did the Org exist before COM/Days?

We know it started AFTER BBS, but we don't know exactly when afterwards. Some people say a few days afterwards, other say a year later. If we have concrete proof of either, I would like to see it.