Dear Ms Khangkarn
Please note that it’s unlikely that your application will be finalised before 11 August 2015.
The date (or date range) on which the planned marriage ceremony may take place (shown in the letter from the marriage celebrant) should be set far enough in the future to allow for the time it takes to process your visa application. The department’s current service standards for Prospective Marriage visa application processing in Bangkok is 12 months.
A Prospective Marriage visa is a temporary visa that remains valid for 9 months from the date the visa is granted. If you are granted a Prospective Marriage visa, you must enter Australia and, after that entry, marry your intended spouse (your fiancé(e)) within the period that the visa is valid.
I appreciate if you could please provide a confirmation of your revised wedding date from your celebrant.