Jeff has a good answer there, but I'm thinking Houston will beat both Green Bay and Baltimore at home. I would look to Week 10 at the Bears as the Texans first loss. Then they have away games Week 12 with the Lions (Thanksgiving) and Week 14 against the Patriots that will be tough. I'm guessing the Texans will have 2 or 3 losses at the end of the regular season.
Atlanta, I'd peg them for 3 or 4 losses. I think their first loss will be Week 8 at the Eagles. Then they have the Cowboys Week 9 at home and at the Saints Week 10. They likely will lose 1 or 2 of those games in my opinion.
So I say the Falcons lose for the first time Week 8 at the Eagles and the Texans lose for the first time Week 10 at the Bears.