However, whilst you may book your celebrant earlier, legal notice can not be given more than 18 months before.
To understand the Australian Government's position on Marriage, download this pdf file
Giving one month's notice means you are able to marry one month later:
If your Notice of Intended Marriage is received by your celebrant on the 1st January, the earliest you may marry is the 1st February.
If your Notice of Intended Marriage is received by your celebrant on the 17th May, the earliest you may marry is the 17th June.
If the date is so late in the month, that there is no matching number of day in the next month, then the next available day is the day upon which you can marry.
Giving your celebrant Notice on the 31st January, means you may marry on 1st March but not earlier.
Giving your celebrant Notice on the 31st August, means you may marry on 1st October but not earlier.
To get married earlier you would require a Shortening of Time from a Prescribed Authority.
But this requires special circumstances and is by no means guaranteed. Your celebrant can provide you with information on this.
Completing the Notice of Intended Marriage Form
If possible, print out the form double-sided.
Do read the information notes before starting to fill in the form.
Do not sign the form until you are in the presence of one of the witnesses listed on the form. Often this will be the celebrant you have chosen but there are other options if you are not meeting your celebrant at this stage.
The date your celebrant receives your Notice form is the date that determines the start of the one month notice period.
If necessary you can send your Notice initially by post, fax, or email and give your celebrant the original when you meet up.
Preferably you should complete the form together but if either you or your partner is not available to sign the form initially, one of you can sign at a later date before the marriage. Your celebrant may require confirmation, for example by email or phone, that the other party is aware that the Notice has been lodged.
Please note: Surprise weddings, where one of the parties to the marriage has not given or been given, a clear month's Notice are not acceptable under the Australian Marriage Act.
If you are overseas, then signatures can be witnessed by a Notary Public or nearest Australian Embassy or High Commission. This may take time and be costly, so do investigate your closest witnesses as soon as possible.
Contact your CCN civil celebrant as early as possible to save any last minute hassles with lodging your Notice of Intended Marriage.