• The user posts before registering, the post is stored in queue.
• The user can take up to a week to complete registration.
• The user finally completes registration 5 days later.
• Posts stored in queue go live with a 5 day old timestamp.

I think the timestamps of the original queued post are used when the post goes live. 

By observation I have seen posts made minutes before the user registers ( based on All Activity )

I have yet to test or see a delayed registration and what happens to the post - would it not show up in the first few pages of activity because it was in the past?

I would think that the post that was queued would be reflective of the timestamp of one second after their registration timestamp. 

 

 

It makes sense to preserve the original post date, as the user was a guest who posted before create the account. I would post this as a suggestion: https://invisioncommunity.com/forums/forum/499-feedback-and-ideas/