Out in Singapore the Gold Xs Max was (predictably) the first to sell out although it was nearly 30 minutes before shipping dates on the 512 slipped, then the 256 and finally the 64. Space Grey was an hour behind that and silver is still available in all sizes for 21st. Xs, all models still available for 21st delivery (3 1/2 hours after opening). All in store pickups disappeared within an hour but that may represent the limited capacity of the one Apple store here to have people go and physically pick up.
Feels like Apple got the production line going earlier this year. People who were used to the Plus size and didn't jump last year now have the X technology in a larger phone so they're popular, the Xs offers little enough over last year's X that direct demand is a bit lower. Note that the majority of consumers here buy on contract from the telcos, I think the rush for Xs Plus when those sales open is going to be crazy, the Xs, better than direct sales as people on 2 year contracts who couldn't move last year will do so now.
I sat this one out as I don't want a phablet and the Xs didn't really offer enough over the X. Quite excited for the Xr launch, that would be a great replacement for spouse's 6 and I can get a funky colour too.