Around 3am EST, waves of fans started downloading the PTR 3.1 You can download it at the following link once you have logged in to your WoW Account. First, you needed to download the old PTR designated:
WoW-126.96.36.19974-PTR-US-Installer-downloader (old PTR installer)
Once you installed it, you would be prompted to download an updated Launcher. That’s when you actually download the PTR 3.1 which takes an approximate download time of 30 minutes on DSL/Cable.