So, how's the prepatch event going to work?

[Punyelf-draenor (Punyelf)]

You can also see that post and the blog post direct via the forums/blizzard

The Cataclysm Classic Pre-Expansion Patch Goes Live 1 May

[The Cataclysm Classic Pre-Expansion Patch Goes Live 1 May] You’ve toppled the undead armies of the Lich King and ended Arthas' reign. Now, Deathwing, The Worldbreaker, bursts from the heart of the Maelstrom, unleashing his rage. All will burn beneath the shadow of his wings. Your new journey begins with the pre-expansion patch — the Shattering of Azeroth— on 1 May and continues with the launch of Cataclysm Classic on 20 May 2024 at 23:00 BST worldwide. View Full Article

The Cataclysm Classic Pre-Expansion Patch Goes Live 1 May - WoW