I'm in exactly the same boat. Changed status today, also 12 pro blue. I think it orignally said I would get an updated delivery date when it changed to preparing to ship, but now it says new delivery time will be given after it ships.
Either way, never mind. It doesn't matter how impatient we are, it will arrive when it arrives.
I've read some people say it shipped for them within 24 hours. Others have waited days, up to a week. I guess it is impossible to know. Enjoy your new phone when it arrives.
(I'll just keep refreshing order status every 30 seconds :D )