When preparing to marry, an important factor is the NOIM or Notice of Intention To Marry. This form must e lodged a minimum of one calendar month before your Wedding date, and no earlier than 18mths. Usually your Celebrant will fill this out with you, ut in some cases when you are in a different town or country, you can have the NOIM witnessed by a Notary Public, JP or other person specified on the notice.
I like to get the NOIM out of the way ASAP so we can dive into the fun stuff! You can download an NOIM online by following this link https://www.ag.gov.au/FamiliesAndMarriage/Marriage/Documents/Notice-of-intended-marriage.pdf