I don't have any personal experience, but as New Year is prime time I wouldn't imagine the flights would get cheaper near the time, I think they are more likely to go up.

luci

Just be careful, the flight maybe cheaper, or even go down, but the fuel charges are going up. If you book now, unless they go up over a certain percentage 2-10% depending on the length of your journey, hopefully you will not have to pay any more.

I would be inclined to book sooner rather than later, however over the past couple of years both British Airways and Virgin Atlantic have had seat sales towards the end of August over the bank holiday weekend. You could take a chance and wait a couple more weeks to see if similar happens this year - but you may need to be flexible over travel dates. I wouldn't wait any longer than end August before booking.