I am not exactly sure if the event is functioning as intended. At the moment, Stormwind is absolutely overrun with ghouls which are rampaging through the streets and slaughtering everything that goes. The auction house, vendors, and classic gold wow even the bank are all unusable--which might be frustrating for players who, once the event is actually reside, are only trying to go about their day to day business.
Over on the WoW subreddit, players have also found ways to attract the zombie infestation out of capital cities, making entire areas of Azeroth uninhabitable.
Fortunately, WoW sport developer Jeremy Feasel affirmed the zombie invasion portion of the event is only going to be busy for a couple of hours throughout the day rather than all the time. I'm actually a bit disappointed with that, honestly, because I think it'd be fun to find yet another all-out, 24/7 invasion which gamers need to try and contain--something similar to World of Warcraft's infamous Corrupted Blood incident.
Players can also venture to the arctic wastes of Northrend to fight bosses and earn powerful loot, and there's also a new story quest to try out.
If you're a WoW subscriber, you can check all of this out today by buy classic wow gold following these steps to get the public test server. Otherwise, you can wait till the event inevitably starts sometime in the coming months. But now that it's about the PTR, it'll likely be occurring sooner rather than later