Yes8s - Just dropped yours in the mail.
The postal service quotes times for their more expensive shipping types, but for first-class, all they list for time is "Varies", sorry.
If anybody knows the typical first-class delivery time from the US to Aus. please post it. If I find out I'll let you know.
OTOH, DX took 37 days to get these to me, so it's gotta beat that by a bunch!