I think you should wait, my device got auto updated with Jelly Bean 4.1.1 -Settings --> About ----> Software Update-->Update (also tick auto update). I think devices bought from Qatar are getting updated by date of purchase. I got my device updated last week but my friend still didn't get the update. You shouldn't risk updating the custom developers versions as it may cause battery drain, other system issues. I wont take risk for device like S3. You must get hold of original update.
I think you should wait, my device got auto updated with Jelly Bean 4.1.1 -Settings --> About ----> Software Update-->Update (also tick auto update). I think devices bought from Qatar are getting updated by date of purchase. I got my device updated last week but my friend still didn't get the update. You shouldn't risk updating the custom developers versions as it may cause battery drain, other system issues. I wont take risk for device like S3. You must get hold of original update.