The 28th seems most likely to me. Aside from them saying in september around 2.38's release that 2.4's only a month away (meaning it shouldn't be november), the 21st would be before the European fanfest. And while that should still give people a few days to do patch stuff, I imagine they would prefer to launch the patch after the EU fanfest is over so people are pretty much guaranteed to have plenty of time to have fun with the patch.

We'll probably find out on the 19th though.