I agree with the OP's supposition that watches will arrive early.
All mention of the 24th is removed from Apple's website. There's no issue if people get the watches on the 23rd, because no one will show up at an Apple store on the 24th for them anyway. They don't have any to sell.
So, rather than sitting on them all, why not get them out. It appears the infrastructure is in place now anyway.
I'm not saying it'll happen, but I have suspected that they might get them out early since they don't list a release date on the website anymore, so they don't have to worry about the "wait in line" crowd to be upset that the "mail order" crowd got their device first. They've been available to see in stores for over a week now, so there's no incentive to keep controlling when and how people interact with the product any further.
Just putting it out there. This isn't a typical launch. Maybe Apple is doing its "Think different" thing again, applied to themselves this time.