This is just my personal experience but I found prices to be the cheapest approximately 2 months out on our trip.  We went last June and paid about $700 each from Houston to Dublin.  I checked daily for quite a while and noticed some patterns that developed.

*Cheapest to fly on a Tuesday or Wednesday
*ticket prices dropped when I looked Tuesday-Thursday.  Maybe airlines know most people look at these prices on the weekends?  Dunno...
*Trip Advisor was a really valuable tool for airfare checking.  Some of the airfares are only good for 1 person (i.e. 1 fare sells then all the other prices go up.  Yes, I'm looking at you, Delta) so you need to put accurate data in the tool but it really helped. 
*Keep an eye out for fare sales.  They pop up at the oddest times.

Anyway, its all a crapshoot so I would suggest setting a price target and as soon as you see that number, jump on it.

SCJag,

Welcome to my forum. I fly out of Atlanta too. Delta flights are usually more expensive than the other airlines. Also fares are slowly creeping up as plane capacity declines. Sign up for their newsletters. Moniter their website every day for deals.

Keep in mind that June is the season. Airfares will be higher than off-season or shoulder season. But keep at it - and when you find a low fare don't hesitate to buy it right away.

Look for spring sales starting after the first of the year.

Michele

There are sales going on now.  Check out Kayak.com