Hawkesbury Post contacted all...
Christmas in October…
Yes, it is only October but Australia Post has just announced its Christmas postage deadlines. Better early than late…
There’s a December 12 postage deadline to guarantee parcels will be delivered Australia-wide before Christmas Day, and December 19 is the cut-off date for guaranteed Express Post deliveries.
International Economy parcels need to be in the post box by November 9 for the UK, and November 23 for New Zealand, for example, but if using Australia Post’s courier service – the quickest but most expensive way to post overseas – December 9 is the absolute cut-off date for all overseas destinations.
More info here for specific overseas destinations: https://auspost.com.au/christmas