It's always been AU time for me. If you accept a promo ahead of time it won't show in your promo counter section but as soon as it goes live it'll show there.

Thanks. By AU time do you mean AEST?

I noticed my number of remaining store listing times roll over in US time hence my confusion.

From experience it kicks in at midnight tonight and ends at midnight on 31st. 

Yes, AEST (or daylight saving time in summer).

Some people seem to have their normal free listings renew on US time but I think most of us have them renew on Australian time. If I were you I'd probably keep an eye on your promo area and take note of when the promo appears there - and don't start listing until it appears. My invoices are worked out on US time (16 hours behind AEST).

Yes

I am a little confused by your comment "I won't have a stack sitting in unsold" or words to that effect?

So with this offer, I am correct in assuming that you also pay no listing fees?

If so it has to be a winner.

Perhaps I am missing something vital, is it better to go for free listings or this offer?

The 7506 offer that meekamag2 posted a link for is to list as many items as you like without paying any listing fees. That means unlimited listings so if you've got anything in unsold waiting to be relisted you can relist ALL of them without paying insertion fees.

None of them worked here either, not that I'm surprised.