If you aren't getting a notification about a pending update yet - don't panic! As always, the roll-out is happening in stages, with some markets getting the new software earlier or later than others. Still, if you can't wait, you can always check if the update is available through Samsung's desktop program - Kies. Software updates tend to arrive there earlier than over-the-air.
This update should bring the software version of your smartphone to I8160XXMC8, and it's going to incorporate all the key Jelly Bean features like Project Butter, Google Now, enhanced keyboard and more. Of course, Samsung's custom features will also be on board. It's not clear yet if the TouchWiz Nature UI will be part of the update, but it certainly makes sense for it to be included.