Hi Erdal, congratulations on your Xperia Z tablet and welcome to the forum. Nice of you to become a member of Android Tablets. Unfortunately. as mentioned, all you can do is wait and see if Sony puts out an update or not.
BTW When you get a chance, please go to your profile and fill in the Tablet / Device entry. That way folks will know which tablet you have without you having to tell them every time.
Welcome to the forum. Is your experia new? I really like mine and my wife likes hers as well. We haven't received notification of a kit-kat update either. Funny thing is, they do not all come at the same time. My wife had her 4.2 long before I did.
Thanks a lot for your comment jbenham. Actually I bought a new but xperia z1 tablet. And havent received the notification yet. But it is written on Sony s website that 4.4 has already been available. Moreover I went to a store today and I saw a Z1 with 4.3 therefore notification must come. I also like my tablet but for I bought it those apps cannot be used only with kitkat. Therefore I am thinking to change to SAMSUNG.