If we judge by the development pace of first 5 months since Hornet's release, late 2020 or 2021 is more likely than 2019.
Given that AGM-65E has taken this much time, the truly complex weapons and sensors like A2G Radar and SLAM-ER will probably take vastly more time to develop.
It may sound discouraging, but think of it like this; The F/A-18C Lot 20 is an incredibly complex machine and it has more sensors & different weapons than the rest of DCS modules combined.
And some of these weapons, countermeasures and sensors have never been seen in DCS before, so it's to be expected that Hornet will take longer to complete.