Reuters claims the first commercial of C919 would be on Sunday.
yep, confirmed here MU9191 and MU9192
Makes a lot of sense to fly SHA to PEK. Big stations. Plenty of media coverage for MU. Can easily fix issues if aircraft has any problems. About 5 block hours, which is quite normal for a new aircraft type going into service. Longer term, they need to raise that to about 10 per day.
IIRC, when ARJ-21 entered service, it was only doing 1 to 2 hours a day. As you can see, C919 is already aiming at much higher target