After a few days back owners of the international version of the Samsung Galaxy S3 (GT-I9300) were treated with leaked builds of Android 4.1.1 Jelly Bean, now it’s time for the first US carrier-specific JB build to hit the web.

A leaked version of Android 4.1.1 Jelly Bean for the T-Mobile Galaxy S3 (SGH-T999) has made its way to the XDA-developers forums, courtesy of Senior Member LuffarJoh. The file is supposed to be identical with the production build that should arrive in the coming weeks.

To install the leaked Jelly Bean OTA on your T-Mobile Galaxy S3, you will need to apply it over the stock ROM, because the patch checks for the integrity of the files before installation. If you tampered in any way with the ROM on your Galaxy S3, you will need to revert to stock before proceeding. The next steps seem simple enough – download the OTA file (273MB) and apply it from the recovery menu.

In case you need a refresher, rumors suggest that Samsung is planning to roll out Jelly Bean on the Galaxy S3 at the end of August, at least for the international version. The rollout date should coincide with the Unpacked event that Samsung will hold on August 29 at Berlin. Of course, US carriers are not exactly known for collaborating well with manufacturers when it comes to applying software updates, so the Jelly Bean update for US carrier-specific versions of the Galaxy S3 might come with a slight delay.

If the thought of the buttery smooth Android 4.1 is too much to resist, and you own a T-Mo Galaxy S3, you might want to give the leaked OTA a chance. Before that though, make sure to go through the XDA thread here and, as always, remember to perform the due diligence.