The first firmware version that has been certified for the Xperia E1 (D2004, D2005) has just appeared on the PTCRB website. It comes in the form of build number 20.0.A.1.8.
Additionally, the D2105 model of the Xperia E1 dual has also appeared on the PTCRB website, following the D2104 model that was certified last week. It comes with the same 20.0.B.0.68 build. All of these firmware builds relate to Android 4.3. Hopefully, the Xperia E1 and Xperia E1 dual are on track to launch next month.
Thanks Ben and difwwh!