All the Walmarts near me too (although that restriction has been lifted for everything but .22LR).
As for announcing a time, I haven't seen that before. I think there's good and bad to that. It's good for the casual buyer who can't wait outside the store every morning before it opens in hopes that there's ammo available. But at the same time, now everyone will be at the same store at the same time for the same limited ammo. No chance to get lucky and happen upon a late shipment being unloaded (which has been the only way I've been lucky enough to get .22 ammo the past 18 months). If they really want to 'discourage' scalpers, they should make a concerted effort to randomized when the ammo goes on the shelves. Not even the most dedicated scalper can be there all day every day.