Book a ticket when you need it. And no, there isn't. But its a qualified "no". Research suggests that if you buy your ticket when most people do between one and four months before you fly you're likely to find the lowest price. Don't push the button too early or too late, because fares tend to rise, especially as you close in on your departure date

You may think you need a credit card to purchase an airline ticket. But a debit or prepaid card will work just as well. And your options may even expand to cash and checks if you book your flight through a travel agent or if you purchase your ticket at an airport ticket counter.

Some airlines may request you to enter your passport number when booking an international trip, but this information is not required at the time of booking. However, you must present your passport at the airport to TSA employees before you will be allowed to board an international flight.