Grab those calendars, AT&T customers, because the big blue operator just announced when it'll begin selling Samsung's Galaxy S 4. AT&T has revealed on its official Twitter account that it'll begin offering the 16GB Galaxy S 4 in stores on April 27, aka this Saturday. Pricing for AT&T's 16GB Galaxy S 4 is set at $199.99 with a two-year contract, and the carrier has said that it'll offer the device in both Black Mist and White Frost.

There's also some good news for AT&T customers that plunked down their cash last week to pre-order a Galaxy S 4. PhoneDog readers Jesse and JLPerez have received emails explaining that AT&T will begin shipping out pre-ordered units earlier than it had anticipated. The operator says that any subscribers that snagged a Galaxy S 4 early could receive their device as soon as April 25. 

It's worth noting that, while AT&T has previously said that it planned to sell both the 16GB and 32GB versions of the Galaxy S 4, today's announcement specifically calls out the 16GB model as being available on April 27. It's not yet clear if the 32GB version will also hit on that date or if it'll be coming along later, but we'll be sure to update you once we hear more. Have you pre-ordered your Galaxy S 4 yet? If so, which model did you opt for?

Thanks, Jesse and JLPerez!

Via @ATT