In general, when booking your flight to Austin, January is the cheapest month on average.
From most locations, booking your flights to Austin around 55 days prior to your departure date finds the best deals.
On average, the cheapest flights to Austin are found when departing on a Saturday. 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 Austin when looking for flights with afternoon departure times.