As it stands, Herod is going to be an absolute mess for weeks if not months. Like completely unreasonable for the average person.
10k+ queues when people are actually playing the game are going to take HOURS (plural), not minutes. They aren’t just reserving a name and logging off. I played on Kil’jaeden (generally high, but nothing like Tichondrius, Illidan, Archimonde, Blackrock etc.), and I still remember waiting for 30-45 minutes every night to get through mere 2-3k queues when major patches dropped. Herod had 12k during name day, and that will probably be its floor during primetime at least for the first few weeks as even more people freshly sub and join the highest pop server they can see.
Then, once you finally log in, assuming server stability, forget finishing any quest that requires open world loot spawns (i.e. the boxes in Tirisfal, cactus apples in Durotar), or killing named mobs (Sarkoth, Samuel Fipps…), etc. Every spawn location will have groups of people waiting to jump. These will already be a problem for other servers on launch day (think the stress test), but Herod will be a totally different animal. Hopping on a different layer won’t save you. You might be better off getting to level 10 via exploration and graveyard hopping, skipping the 1-12 zones altogether.
Blizzard’s provided an out, albeit an imperfect one. Lots of people were completely unaware that Stalagg was even open until their name was already gone, guilds are splintering as they debate whether or not to jump ship, etc. etc. It’s a mess.
At this point though, any complaints about Herod on launch day, if officially acknowledged at all, will probably just be referred to the “Overcrowded Realm Update” post, made 10 days before the official launch. Their hands are clean (in their eyes, anyway).
Blizzard is not going to increase the cap. This is has been confirmed. They will not release another server until Stalagg is also full. This has also been confirmed.
There will be a LOT of frustrated players on Herod, especially if they have limited time to play each day. If that’s you, pick a different server. Herod just won’t be viable for you.
The others? If you wanted supreme competition, you’ll have it… in literally every aspect of the game. Imagine how quickly your items will be undercut on the AH with that many people, for example. Prices will be completely unstable, and unless you actively watch your postings you might not sell anything at all. It’s going to be a battle to do much of anything, even within your own faction.
Don’t let the hype of a “full and bustling server” ruin your experience. Add a funky vowel to your name and take the out for your own sanity. Time zones don’t matter. Ping doesn’t matter. Minority populations of LAm/SAm players don’t matter. Playing the game matters.
TLDR: It’s a mess, no one is/will be happy, game’s ruined. REPENT. FLEE. ETC.