Hi XXXXXXXX and thank you for your question.
If your dates aren't flexible and these are the specific dates you wish to fly, I would suggest booking now. With a close deadline as July 26th, seats are already filling up fast. Prices will only be getting higher. If you are making a connection as well, it is best to book earlier. With multiple planes, it is easier for one of them to sell out causing prices to soar quickly. Unless you are looking at a specific airline here are some helpful websites that you can browse to find the cheapest flights.
http://supersearch.travelzoo.com - this website looks through all the popular booking websites such as Orbitz, Expedia, etc. for the cheapest fare
I have personally found Yahoo Travel to be helpful and cheap as well. here is the link:
http://travel.yahoo.com
You can also search united.com or AA.com for specific airlines. Most airlines offer their cheapest flights on their own websites instead of Orbitz, Travelocity, etc. But is not always the case which would make it worthwhile to check those other sites out.
Don't expect anything cheap, however. With such a long flight only a month and a half away, you can expect to pay over $700 per person.
I hope this has helped. Please click the accept button so I may get credit for my work.
Happy Travels!
-Grant
Internet Researcher
I have been doing internet researching for over 4 years.