An Android 4.3 firmware build for the Xperia SP (C5302, C5303, C5306) was already certified with build number 12.1.A.0.253 back in December. However, it looks like Sony wanted to iron out a few more bugs, as a new build with version number 12.1.A.0.256 has just been certified by the PTCRB. If this is the final version for release, we would expect it to hit handsets within a couple of weeks.
Thanks Christian and Patryk!
