Good idea, I will try and work that in. Only problem with that is how dependent it would be on a large amount of invitees posting when they registered code and when they got in.
Suggest that people post the the following format which is copied directly from My Account->Code Redemption:
11.15.2011 Star Wars™: The Old Republic™ Standard Edition Pre-Order
It's not too hard to verify what are obviously outliers. (For example if I claimed I was already in.) Things will start moving so fast that if you are a few days off it generally won't matter and anything that falls outside of reason can be ignored as trolling.
In short you are smart enough to put together this thread thus you are smart enough to filter out obvious trolling.