For me, it didn't go live until 1:00pm EST. I got an alert that the sale was live (guessing from installed app). Sales just ok. Not much offered and nothing we need.
How do I access the sale? My mobile app doesn't look any different than last night and I can find no mention of the sale. It should have started 45 minutes ago, per the comments above.
Just a note.... Our closest Walmart said they only got 5 iPhone 5's in stock at that price. Other area Walmarts said they also received limited stock of the iPhones and iPad.