In general, when booking your flight to Perth, March is the cheapest month on average.
Most flyers found that booking flight tickets 45 days in advance of their planned departure date is, on average, the best time to get cheap flights to Perth.
On average, the cheapest flights to Perth are found when departing on a Tuesday. Try to avoid departing on a Friday, as this is usually the most expensive day.
On average you can find the best deals on plane tickets to Perth when looking for flights with afternoon departure times.