Don't try to shoot me with your shotgun. This post is not about official JB update in Sony Tablet S. It is about unofficial Jelly Bean updating in your tablet.
I have tried to help you by this guides which work:
1) Sony Tablet S: Update to the Latest Android 4.1 Firmware with One Click Tool
2) How to Update Sony Tablet S,P and Xperia Tab with Android 4.1 Jelly Bean
3)Sony Tablet S gets chunky update
I shall be happy if it helps
I have tried to help you by this guides which work:
1) Sony Tablet S: Update to the Latest Android 4.1 Firmware with One Click Tool
2) How to Update Sony Tablet S,P and Xperia Tab with Android 4.1 Jelly Bean
3)Sony Tablet S gets chunky update
I shall be happy if it helps