in 2008 they were available on stores the next day, so I'd hope they would be the same, it also means we get them before America.
Though it is entirely possible they won't be available for a week or more, in 2008 they announced them at a special advent that they could plan around the MacBook pros availability, whereas wwdc has had a date planned for a long time, so they might not be ready yet, if that makes sense.
What is the typical lag time for Amazon to get the new Apple products after they go on sale on apple.com?