This is more of an AusPost question, but the answer as of the 18th of September 2019 is that the tracking status 'pending – no events yet’ means that the item hasn’t been scanned yet.
This could be because it:
Hasn’t been posted yet, OR
Was posted in a street posting box, which means it will take a little longer before it’s first scanned, OR
Was part of a bulk mailing where items have been posted over the counter in bulk but not scanned yet
Please try tracking your item again in 24-48 hours.