There's no easy way of knowing for GTC listings, either, since they could be listed for X amount of time before their first revision (if they've even had one), and the year doesn't show in the newly listed sort order (they are in descending order though, so if there weren't many listings, or someone had the time and patience to go through every page, they'd know when the years ticked over because there'd be Jan > Dec > Nov.... back to Jan > Dec etc in cycles).
For 30-day BINS, there's no way to know when it was first listed, if it's been listed for more than a couple of cycles, but it will show the date of the new listing, and you can at least see if there's been a couple of previous runs in completed listings.
It's kinda funny because I saw recently via the make an offer info that it's part of eBay's advice to check when an item was listed on the site because sellers might be more likely to negotiate if the item has been listed a long time, but they don't actually provide any tools to do that properly. o.O
