Well, that was quick. It’s April 1, and Samsung has already started rolling out the security patch for the month. The update – arriving as build number J320FXXU0AQC3 – is currently hitting Galaxy J3 (2016) units in Europe.
Some regular bug fixes as well as device optimizations are included as well.
As is usually the case with OTA roll outs, it might take time for the update to hit your device. Meanwhile, if you feel impatient, you can manually check for the update by heading to your handset’s Settings menu.