KitKat should start arriving over the next few days or weeks for owners of the Sony Xperia Z Ultra, Z1 and Z1 Compact.
Sony was quick off the mark to announce which Xperia devices would get KitKat, but until today it hadn't said when the update would arrive. Some five months after Google released Android 4.4, which has since had two maintenance updates, Sony is done tweaking the OS and will begin pushing it out to the three smartphones "now", according to Sony.
Meanwhile, the other devices it promised would get KitKat — including the Xperia Z, Xperia ZL, Xperia Tablet Z, and Xperia ZR smartphone — will get it from the middle of the second quarter of this year.
Sony also announced that KitKat will be coming to some of its lower to mid-range devices including the Xperia T2 Ultra, Xperia E1, and Xperia M2, but it hasn't said when.
Some of the changes Xperia owners can expect with the update include performance and UI optimisation, as well as Sony's tweaks to the Android Status Bar and Quick Settings, which will be customisable and will prioritise notifications according to user need.
The update will also bring changes to Sony's native apps, such as messaging, MyXperia, and Smart Connect, as well as Sony's line-up of media apps, such as Walkman, album, and movies. It's also adding Sony Entertainment Network cloud services integration, but it notes this will vary by country and carrier.
Users can also start experimenting with Sony's Xperia Themes, which it launched earlier this month. With 280 themes to choose from, it's the company's answer to third-party home launchers.
The KitKat update for Sony's headline smartphones comes as it readies to begin selling the Xperia Z2 and Z2 tablet, which were announced in February and will ship with KitKat onboard.
Samsung kicked off its KitKat roll out last week in the UK for the Galaxy S4 and Note 3. The update should be available in coming weeks, according to Samsung.
Meanwhile, HTC's KitKat rollout for the One was recently stalled due after early complaints over bugs.
Read more on KitKat