If you're getting confused about when the DTV transition will happen, you're not alone. As it stands today, Congress has passed a law to delay the DTV transition until June 12th; the bill is currently waiting President Obama's signature but he has publicly endorsed the idea. So now that the date is nice and firm lets add a massive amount of confusion into the mix.
According to the FCC, up to 61% percent of TV stations will be allowed to make the switch earlier than June 12th. So, rather than have one unified date for the entire country, Congress borked up the entire process by allowing some stations to convert as they please but everyone must convert by June 12th.
The moral of the story is that you need to watch your local stations to see when they will make the switch. This is true for about 6.5 million people who may be affected, while the other 296.5 million people, who are ready, don't need to do a thing.