It started around 3am this morning on all three sites - Amazon, B&N and Smashwords (and thence to Kobo, Diesel, etc).
Smashwords will probably be ready later today, as they are generally the fastest. The extended catalog (Premium Distribution) probably won't be ready for about a month, however.
Amazon should show later this weekend, followed by B&N.
All three sites were submitted (almost) simultaneously, instead of on a staggered plan.