I see this question asked so often, that I decided to dedicate a Blog post...
There is no one-size-fits-all answer. Processing times vary across visa categories, embassies and countries of origin. The Department of Home Affairs lists average processing times for most visas on their website, but it's exactly that: an 'average'! A lot of people mistake these time frames with an 'up to...' and then get frustrated if their visa takes longer to process.
So here is a rough guide (valid October 2018)
600 Visitor: 17 – 31 days +
187 Regional Sponsored Migration Scheme (DE): 22 – 24 months +
189 Skilled Independent: 8 – 11 months +
500 Student (Higher Education): 30 – 39 days +
309 Partner Visa (offshore): 13 – 17 months +
820 Partner Visa (onshore): 21 – 26 months
155 RRV (5 years not meeting residency requirements): 67 days – 5 months +
Updates are published on a regular basis here
Remember, the Department of Home Affairs doesn't offer any guarantees that your visa will be processed within a certain time frame. So it is your own responsibility to plan for enough time to make your arrangements.
To some part visa processing times are out of your control. You cannot control staffing shortages or bottlenecks. However, what you are able to control is that your application is lodged complete, i.e. with all required documents. Make sure your document uploads are of acceptable quality and translated where required. If your case officer can't decipher your documents, if documents are missing or not translated... all these things will impact negatively on the processing time of your application.
To ensure your application is lodged timely and meeting all of Immigration's requirements you can hire a Registered Migration Agent to assist you. If you would like to discuss your options please feel free to contact us for a consultation. We offer face to face consultations in Melbourne and Shepparton, as well as by Skype, WhatsApp or email.