purchasing airline tickets

[thinkingbouteurope]

Good afternoon ...

I've noted that on Kayak.com they provide price trending for specific flights within the last 90 days. Is there any rule of thumb as to the time frame to purchase. I plan to leave Sept 4, return Oct 4 (Newark - Geneva, Frankfurt - Newark), so right now I'm 4 months before my trip. I've been told that airlines allocate a certain number of tickets at a given price, which would indicate that purchasing earlier is most cost effective. Is that accurate? Is waiting for a bargain price risky?

Thank you for any insight or information.

[MuvverRussia]

There's no generic trend. Personally, from my experience flight prices only tend to go up, especially on long haul routes. That said, you may get lucky and get a sale, but it's definitely a gamble.