If you are sending cards and gifts interstate or overseas the you will need to get moving and have everything posted at least 2 weeks before the 25th.
Check international postage deadlines with Australia Post (or your country’s carrier) to give yourself plenty of time. This year International post needs to be sent by 4th December, and mail within Australia needs to be sent by 12th December.
Last year I sent a parcel interstate on 14th December and it didn’t arrive at its destination until 7 January.
Be prepared! Post your items early.