The hard copy will be needed later when you adjust status, so put it in a safe place. USCIS has been behind on their online system, they have been dealing with a flood caused by the fee increase last summer.
The next step is to give it two weeks or so and then call NVC for case status, do not attempt to use the USCIS case number on NVC's automated system, it wont have anything for K-Visas, you need to talk to an operator, or you can just email NVC @ NVCINQUIRY@state.gov in your email list USCIS case number, and the Names+DOB of beneficiary, and petitioner, they will reply in a few days.
Once it leaves NVC, it will be 3-4 months before Guangzhou will "Receive" it and send out packet 3.
While waiting for this, I recommend joining and using "A Candle for Love" that site's information is the most extensive for preparing to the interview in Guangzhou.
http://candleforlove.com