Allakhazam says that Deity-Specific items were introduced on Apr 10th, which was 2 months after the release of Paineel and two weeks prior to the release of Kunark. April 10th was also the patch that revamped Kerra Ridge and Splitpaw.
https://everquest.allakhazam.com/history/patches.html
Edit: I don't know how much weight Allakhazam carries here or with the devs, but I've found it increasingly difficult to find any actual official patch notes from official sources from around 2000.