Hi, in our case, since we know that visa processing takes years, we opted to wed first and update our documents prior application. We don't want to update our personal details in the middle of our application as we're afraid that it might cause confusion or issues.
Advantage of getting married first is your personal documents/info are already updated upon application. Also, one or either of you can act as the main applicant, while the other one is dependent, more cost efficient than applying separately as single.
Cons - application will take longer as you need to update all your personal documents first. Another would be when you're single you will automatically have additional 10 points, but if you are married, you will only earn this if your partner has a valid positive skills assessment (5) and competent English (5).
Hope this helps. I'm just sharing our case. If you have an agent, better seek their advise.