In general, when looking for the cheapest flight to Las Vegas, try to choose a flight departing in February for the best deal.
From most locations, booking your flights to Las Vegas around 53 days prior to your departure date finds the best deals.
In general, booking your departure to Las Vegas for a Tuesday represents the best deal on airfare. Try to avoid a Friday departure to stay away from the highest prices.
On average you can find the best deals on plane tickets to Las Vegas when looking for flights with midday departure times.