If you're interested in applying for one, you might want to take a look at The Australia Visa from Malaysia that conveniently allows access online 24 hours every day, 7 days per week. Let's pretend you're getting an extremely spontaneous offer to travel or some personal reasons force you to take on the journey in a very brief time. Should you need an eTA, it's advisable that you apply for it when you plan your journey, instead of waiting until you're ready to travel.