A decision can be made anytime after the interview. You won’t receive a decision on the day of your interview. You will receive a decision sometime later in writing.
The DIAC aims to make decisions within 90 days of lodging your application. However in practice this does not often happen, sometimes because external checks take a long time. If it does take longer you shouldn’t be worried about this.
Sometimes your case officer may ask you to provide more information to support your refugee claims for protection, you must provide this information within the timeframe given by your case officer. To avoid delays with your decision, provide any information that your case officer asks for as soon as possible. If you are cannot provide this information, you should let your case officer know why you are unable to. If there are delays in getting the information, you should let your case officer know when you expect to receive it.