I never actually thought this at first, but I'm starting to think that the Red Wedding may occur in Episode 7: Autumn Storms (the episode being written by George R.R. Martin). If not Episode 7, then at least Episode 8. I don't think that Season 3 will be entirely in the same order as the book. I imagine that we may see all three weddings this season; concluding the season with the
Spoiler
death of Joffrey, and the imprisonment of Tyrion, and the escape of Sansa
. And...I think Jon Snow's story will end following the first wave battle at Castle Black, with the
Spoiler
death of Ygritte
. But, these are just my theories of how the season will play out.