I used to believe waiting to buy airfare was a better plan than purchasing that far out. The stories used to read "I got my airfare for our trip in two months at the lowest I've seen it all year". Unfortunately, the stories lately seem to read "I can't find reasonable airfare and my trip is only two months away".
Against my normal judgement, I purchased airfare for our upcoming trip 6 months ahead of time for what I thought was "fairly" reasonable. I was happy with it...it was within my
budget, albeit at the higher end of what I'd hoped to pay, but they were nonstop flights at wonderful times. Now, as I'm nearing my trip, I'm seeing loads of folks struggling to get decent airfare for the same time I'm going and I haven't seen my flight go any lower in price, not even on Southwest, Airtran or JetBlue.
So yes, if the tickets are within your budget (especially since you're traveling during a very popular vacation time), I'd buy them and be happy.
And don't keep checking airfare prices...you'll torture yourself if they go down, LOL!