As with all ceremonies of this nature, the crew has to practice. Here's a photo of the "manning the rails" walk-through:
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Update 0900 26 October: The New London Day has a report on the commissioning that includes a photo gallery and a discussion of Virginia-class submarine construction timelines. They mention that this is the first year since 1996 that two SSNs were commissioned in the same year. [As you remember, USS North Carolina (SSN 777) was commissioned in May.]
Update 1332 28 October: Here's the Navy website report on the commissioning, with its own photo gallery and a link to a short video report on the commissioning ceremony.